the answer is both quite complex and quite simple...
yes two devices can, to some extent, have the same HWID.
for example on my machine i have a RAID controller
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RAID Devices
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PCI\VEN_1095&DEV_3112&SUBSYS_61121095&REV_02\4&1F7DBC9F&0&58F0
Name: Silicon Image SiI 3112 SATARaid Controller
Hardware ID's:
PCI\VEN_1095&DEV_3112&SUBSYS_61121095&REV_02
PCI\VEN_1095&DEV_3112&SUBSYS_61121095
PCI\VEN_1095&DEV_3112&CC_010400
PCI\VEN_1095&DEV_3112&CC_0104
Compatible ID's:
PCI\VEN_1095&DEV_3112&REV_02
PCI\VEN_1095&DEV_3112
PCI\VEN_1095&CC_010400
PCI\VEN_1095&CC_0104
PCI\VEN_1095
PCI\CC_010400
PCI\CC_0104
The full HWID PCI\VEN_1095&DEV_3112&SUBSYS_61121095&REV_02\4&1F7DBC9F&0&58F0 is probably unique but this is not always true....
this HWID is matched first if it can be found. then the "compatable HWIDs" are matched in diminished order of magnatude. (IE the way they appear in the above list)
with a "super generic HWID" like PCI\VEN_1095&CC_0104 almost any silicon image driver from any manufacturer could in theory be matched with it, weather or not it will work is anyones guess, most of the time it won't, even though theoretically it should.
If windows searches for a driver and selects one as the best match it isn't going to change it's mind. It is a program and will continue to select the same choice over and over until you change the drivers you have available.
It is possible that the two drivers both contain the same HWID like PCI\VEN_1095&DEV_3112&CC_0104 and are both therefore a good match. however if one is signed and one is not it will always choose the signed driver even if the unsigned is a better or even newer driver. if both are signed then the newer is selected even if the old one is from the oem manufacturer and the new is not. PnP is better than it ever was but it is still far from perfect. If PnP worked then we would not be the only game in town for DriverPacks... everyone would simply make their own. It is just not that easy you cant just take a bunch of drivers together and put them in a folder and expect them to work together... That is what we have been beating our heads against the wall trying to do for over Eight Years, and why no one else even comes close to accomplishing what we have. In theory if they had ten years and a team of dedicated people and millions of users to provide feedback they could get where we are now... 
We will see what we can do to help you with your situation... Can you test a pack if we mod it for you?
Jeff
BTW excellent first post and welcome to DriverPacks.net - thank you for helping us to help you... and everyone else in your situation.
