Can't Pin Similar Shortcuts to Taskbar

Just installed my Win 7 upgrade disk. Something has changed from the last Win 7 RC. I've got two shortcuts to Thunderbird. Each includes a profile parameter so that one opens my wife's mail, the other mine.

Previously, I could pin both to the taskbar. Now I can only pin one. Adding a second does nothing. I even tried to "trick" the system by pinning a shortcut to another program and then changing the properties to those of a Thunderbird shortcut, but once the executable file (thunderbird.exe) was applied in the properties it would vanish. I also tried adding the shortcut directly to the hidden folder where they are stored but it still won't show on the task bar.

Two fixes that I'm not happy with: 1) make a copy of the thunderbird.exe and rename it thunderburd.exe. Have one profile point to this copy. Works, but I have to remember to manually update the copy. 2) create a task in task scheduler and run the task link. Works, but it takes half a second longer to run and a DOS box pops up for a second as the program starts.

Adding the quick launch toolbar seems redundant and I don't want another spacer bar sub-dividing my task bar.

So - how do I convince Windows 7 that I should be able to pin multiple copies of the same file executable to my taskbar?

Thanks,
Ric

Actually, if the shortcuts have different command lines you should be able to pin both to the taskbar.
Could you reply with what the exact command lines are for each shortcut you are trying to pin?

It just started working the way I wanted it to. Dragged a link from my Documents folder into the taskbar and it stuck, but found out it pointed to "Program Files" instead of "Program Files (x86)". This time when I fixed it, it didn't vanish. No idea why that worked...