possible to have 2 PS installations on same email adress?

[annalin]

I have an installation of PS 1.3.3 with one email address and today I wanted to make an new installation with PS 1.3.5. Unfortunately (I think!) I used the same email address (but different passwords of course) for this new installation and now I can log in to the Back Office of the 'old' one but there are no tabs and I can't go anywhere in the BO. The new installation works fine but since there are modules missing in BO I wanted to check the old shop and modules in BO for reference (using the same theme in both shops) It doesn't matter if I log out from the new admin/BO or not.
Does anyone know what is up?
Hope I have explained this well. I don't want to have to start all over again with another new installation if it's not possible to have two PS installations with the same email address.
Both installations are made on my local xampp server. In different folders.
Would really appreciate some help, have searched the forum but not found any similar problem in threads.

[olea]

If you have used a different dabase for each installation, it should be OK

[annalin]

Thank you for the answer but
I dont know if it's a different database? (I guess but don't really know anything about these things...) I have this local xampp server that my brother installed. There I have at least 3 different PS working installations (in separate folders) but only these two latest are on the same email address.
So if it's OK why do I suddenly have no tabs in the BO of the PS 1.3.3 installation? This happened only after the new installation of 1.3.5

EDIT
Maybe I should say that during the second installation (1.3.5) I had to change the prefix for the database from ps_ so I named it ps4_ and that seemed to be working but maybe it was wrong?