ATTENTION: Merging will result in the client to mix upload and download from peers of both tracker together. This will result in wrong UL and DL reported to both tracker!
Which exposes a member to getting in trouble for cheating on both tracker.

In your own interest, do that only with public torrents.

Only if the two torrents appear separated, one for each tracker, you are save.

A solution on same torrent is to run two different (instances of) clients.

hum there shouldn't be 2 torrents with same content in the first place IMO hence the reward for duplicate torrents.

I think what he's referring to is if for example he downloaded a torrent from another site, then found that torrent here (or vice-versa). And yes… This is called the re-seed process. It is explained in our upload guide, starting at step 4 where it talks about downloading the .torrent file that you need to seed the actual content with.

As for doing this with two different files on here, this is also possible using the same process. If for example, you're seeding a duplicate torrent (or you uploaded an identical duplicate), you can switch to the original with this process as well.