D-D fusion can be aneutronic when a third body is present like another atom. Momentum conservation requires two products so He-3 and n or p+H-3. There is a very rare reaction <1E-12% of the time that can lead to He-4+ gamma but it is not worth mentioning. The aneutronic D-D is one of the hopes of cold fusion folks. Evidence does not support that this reaction can favor the aneutronic branch in the presence of current materials or conditions that can be reproduced.