The explode tool should honor the geodatabase split policy on multi-part features.

[MDB_GIS]

Currently, if you have the split policy set to duplicate for a relationship class, when you split a polygon using the split tool, it will duplicate the records for you. However, if you use the explode tool, which is effectively doing the same thing, not only does it not copy the record to new features, it seemingly gets rid of the relationship all together. I'm guessing this is because it deletes the original feature and thus loses that relationship, but I'm not 100% certain. But it would make far more sense to me if this tool behaved in the same manner that the split tool did and it honored the split policy. 

[JMutunga]

@MDB_GIS Thanks for reporting this behavior. 

This is a reasonable request that the team can discuss ways to improve.

What I'd like to point out though is that with the 'Keep original features' option checked, the relationship between the two (original) features is preserved after explode operation. You probably already know/tried this (I know it is not an ideal solution for what you are asking) but wanted to mention it for the sake of other people who may see this post in the future.