Debug two process Using GDB

Hi All
I know How to attach a process to beubg it .But for my application I am using client as well server.Both are two separate process .Suppose I need to debug both .How to attach both of them together .Or I have to attach them separetly .

Suppose client process id is 1325 and server is 1355.
Can use
gdb attach 1325 1355.

Please suggest me

Why not debug them as two separate gdb instances? Is there any particular reason or advantage such that you need to debug both the client and server together in one instance of gdb?

Actually I am sing putty.And from there I am debugging .I can debug with two instance but I have to create two putty session then.Is there no other way to attach two process