It's interesting that there is no problem on Windows XP, just on Windows 7 x64. Do you know the problem with long printer names as Microsoft explains in article INFO: Working with Long Printer Names
. I'm quite sure that the IDM developers have not added additional code as suggested by Microsoft to workaround the printer name length limit of 32 characters in Microsoft's MFC library.
Are the first 32 characters of the names of the 4 printers on Windows 7 indentical?
Yes, then you should rename the printers on server and all clients so there is a significant difference in name of the 4 printers within the first 32 characters. This is an issue occurring most likely only when having the same network printer installed several times with different configurations.
In my point of view it does not make sense to have a network printer installed several times with just some differences in configuration. Okay, it gives the users the possibility to print with different settings by simply selecting another printer than the default. But printers also support nowadays different profiles. So instead of having multiple printers installed which in real print all on the same printer, it would be also possible to have only 1 printer and select in the printer properties a different profile when needed. For the main network printer we use in our company we have only 1 printer installed and use the profiles requiring only 2 additional clicks in comparison to having the network printer installed several times with different profiles preselected.