There is no prohibition in the planning legislation on the existence of multiple development approvals over the one parcel of land. However, the operation of s.66(2) of the Planning Act 2016 can sometimes cause difficulties when the conditions of an existing development approval may, on the face of it, appear to be in conflict with the proposed conditions of another development application.
Relevantly, s.66(2) provides:
"(2) A development condition must not be inconsistent with a development condition
of an earlier development approval in effect for the development, unless—
(a) the same person imposes the conditions; and
(b) the applicant agrees in writing to the later condition applying; and
(c) if the applicant is not the owner of the premises when the later
development application is made—the owner agrees in writing to the
later condition applying."
These provisions are sometimes interpreted as meaning that the conditions of any future development approval over a parcel of land cannot be inconsistent with the conditions of any existing development approval. The obvious difficulty with such an interpretation is that future development approvals are potentially bound to the conditions imposed in an earlier and unrelated development approval.
This apparent conundrum was resolved in Liqourland (Aust) P/L v Gold Coast CC & Anor  QCA 248 where the Queensland Court of Appeal considered s3.5.32(1)(a) of the (now repealed) Integrated Planning Act 1997, which provided:
"(1) A condition must not -
(a) be inconsistent with a condition of an earlier development approval still
in effect for the development;"
The legislative provision considered by the Court of Appeal in Liquorland is very similar to the provisions of s.66(2) of the Planning Act insofar as it used the words "in effect for the development". The following extracts from that judgment set out the relevant findings:
"4. The first point: the relevant application of s 3.5.32
 Section 3.5.32 provides that a condition in a development approval must not be inconsistent with a condition of an earlier development approval still in effect for the development. Two relevant questions therefore arise under this section. The first is whether the approval dated 5 March 2001 was an earlier development approval still in effect for the development the subject of the present application. And the second is, if it is such an approval, whether condition 1 contained in the conditions of approval of the Council in its decision of 21 September 2001 is inconsistent with conditions 1, 2 or 3 of that earlier approval.
 The learned Planning and Environment Court judge resolved that first question in favour of Davies by holding that the earlier development approval was for a different development from that the subject of the second. The first was, he said, an approval for the development of a hotel; the second for use of part of the hotel premises for indoor recreation (gaming machines). It would follow from that conclusion, if correct, that the earlier development approval was not one which was still in effect for the development the subject of the second approval and consequently, as his Honour held, no question arose as to any conflict between conditions pertaining to the two approvals.
 The approval of 5 March 2001 was not an earlier development approval still in effect for the development the subject of the approval of 21 September 2001, within the meaning of s 3.5.32. It was one for a quite different development, namely a hotel. Mr Lyons QC, for Liquorland, whilst conceding that the phrase "for the development" means "for the same development", sought nevertheless to construe it to mean "with respect to the land the subject of the same development". In my opinion there is no justification for such an artificial construction.
 It follows that the learned Planning and Environment Court judge was correct in the way he resolved this question. Section 3.5.32 therefore had no application in this case."
Liquorland was more recently followed in Steendyk v Brisbane City Council and Ors  QPEC 47. In its consideration of s347(a) of the Sustainable Planning Act 2009 (which is identical in terms to the IPA provision) the Court said:
" It remains to deal with the operation of s 347(a) of the Sustainable Planning Act, which was also relied upon by Mr Steendyk, to support his argument that the Calder-Potts remain bound by the 2002 court approval, and that no subsequent approval, such as the 2014 change approval, could include a condition inconsistent with the 2002 court approval. He contends that the change approved in 2014, to the north western part of the verandah at the centre of this proceeding, is inconsistent with the condition in the 2002 court approval, requiring fixed privacy screens.
 As already noted, s 347(a) provides that a condition of a development approval “must not be inconsistent with a condition of an earlier development approval… still in effect for the development”. The important words are “still in effect for the development”. In this context, “the development” is the development the subject of the later approval – here, the 2010 approval. The 2002 approval was not an approval “still in effect for the development” the subject of the 2010 approval, because the latter was for different “development”.
It follows from these judgments that s.66(2) of the Planning Act 2016 should not be interpreted as requiring multiple discrete development approvals to have consistent conditions across each of them. Rather, it is clear from these decisions that what is required is that the conditions of a specific development approval and any subsequent related development approval be internally consistent.
Consequently, it is possible to have multiple development approvals that have inconsistent conditions over the same parcel of land. This outcome has a broad application, particularly in circumstances where development pursuant to a development approval has started and the developer wishes to pursue a different type of development outcome which is inconsistent with the development that has already commenced.