We are on release 7/26/13 SP1.  A few versions ago we could go into Sales AR - C and look up by invoice number multiple customers.  Now we can only look up 2 and we have to close that screen and reopen it to look up 2 more.  It was very handy for me as sometimes I only have an invoice number and not the Customers Code.
 
Thanks!

When I'm entering a deposit, it works great!  But if I'm looking up customer codes and just have the invoice number, I use the same screen but it will only let me look up 2 before I have to close and reopen.  Is there a different screen I should be using?

Yes.