Mail.app Trash

[moo.sh]

I don't know how they got there, but today there are two trash folders within my main trash folder, something like this:

> Trash

> Virgin (my account name)​

> On My Mac​

When I delete something from my inbox it is visible in the main trash folder and the Virgin trash folder, but not the On My Mac folder.

What can I do to return Mail to just a single Trash folder?

Thanks.