Okay, first of all, there is no such thing as "mapping folders" or "network drives" on a Mac. Put the whole concept of "mapping" and "drives" into the Windows Recycle Bin of your Windows brains, and empty it. It is of no use to you now, and will only confuse you.
You will have to try to understand what the Mac is doing here. Once you do,
you may not like it, but at least you'll have a better idea of why.
What you're doing, on a Mac, is
mounting volumes. And as far as the Mac is concerned, only whole shares can be volumes.
So if you have, on the Windows server:
C:\sharedfolder\ (a share)
which cointains
C:\sharedfolder\subfolder1 (not a share)
C:\sharedfolder\subfolder2 (not a share)
and you try to
mount
smb://win-server/sharedfolder/subfolder1
The Mac will happily mount SHAREDFOLDER and leave it up to you to find the subfolder you wanted inside it.
If you then try to mount
smb://pc-server/sharedfolder/subfolder2
the Mac will tell you that, indeed, you are already connected to the share (SHAREDFOLDER) and will not understand why you wanted to mount that same share a second time.
If you really want to
mount subfolder1 and subfolder2 as seperate
volumes, you (or the Windows server admin) will have to share each of those folders as a seperate share.
And once again:
1. Forget the word "mapping."
2. Forget the word "drive."