For various reasons, some of which are beyond our control (sorry to be so mysterious), it's not possible for multiple DistroKid users to upload music using the same ISRC.
However, we have good news!
DistroKid is one of the only distributors that makes it easy to route all (or any amount of) earnings from any track, to any other DistroKid member(s).
So if you're moving or transferring ownership of a release from one person to another, simply use DistroKid's "Teams" feature to redirect 100% (or any percent of) earnings from the chosen track(s), to the new DistroKid account.
This will ensure that all metadata, including ISRC, remain intact and unchanged. Another added bonus is that your stats and playlist positions should remain intact.