>When I try to make an account with BIS inputting my BES connected phone pin/emei it says "an account already exsists". This I guess is not strange.
That means someone already created BIS account for your BES device. If it was not you, it is strange.
Use 'forgot password' link on BIS web page and see what password will it bring to your BES device from BIS.
>When try to make a BIS account with my second BB phone which is not on BES, I get something like "unable to make an account".
I wonder where did you get your second BB phone from?