I know of no such regulation or policy that limits an award to only one awardee. If this were a requirements type contract it would be a different story, but you indicated it's an indefinite-quantity contract. It's possible a service or agency (DLA in your case) may have local policy guidance for your situation, but that's unlikely. However, it may be worth checking with your contract policy office.

Of course since this is an IDIQ, you will need to be attentive to the minimum quantity guaranteed to all recipients of the basic multiple award contract.