I asked groupee if it was possible for two boards to share the same file path and they said that the file locking would get out of hand and cause corruption.

What I want is to have two boards and if someone registers on one board they can post on the other one without having to duplicate their registration.

Can anyone tell me why this would be a bad idea? or maybe if it has been done before?

it's been done plenty of times before, even we do this for the test board. It just reads the member files from here.

So is it possible just to restrict registration on the second board and remove the option to change the profile on the second board, then there would not be a major conflict with the file locking, or have you had no problems with it at all?

The main problem isn't file locking, I'll need to poke and prod whoever told you that.

The main problem is that we use the Members directory for much more than just member records. We keep post histories and indexes, private messages, and permissions there as well.

In short, you can't have private forums at all on either board. If you do, the forum numbers are going to end up in conflict, and changing member profiles on one will end up doing fun stuff, such as removing private forum rights on the other.

You won't be able to do any member based topic searches because the post indexes will conflict with each other.

Don't even get me started on private messages...

It's bad mojo, don't do it.

That said, we use it on 2 different sites like that without a lot of issues On both tho, the second installation isn't used much and you have to be careful with private forum permissions.