Combinatorial procuremnet auctions enable suppliers to pass their potential cost synergies on to the procuring entity and may therefore lead to lower costs and enhance efficiency. However, bidders might find it profitable to inflate their standalone bids in order to favor their packages bids. Using data fraom standard and combinatorial procuremnet auctions, we find that bids on individual contracts in simultaneous standard auctions, without the option to submit package bids, are significantly lower than the corresponding standalone bids in combinatorial auctions. Further, no significant difference in procurer's cost as explained by auction format is found.