Just install the new one and see how it goes. They often take care of all of that for you. I rarely bother to uninstall hardware drivers anymore.
Saitek drivers install under a couple of different devices IIRC, you may be missing one. You can always go to device manager and just go through the list, hit properties and uninstall driver, but they won't all be obvious.
I'd just go for it with the new one.
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