Why so many duplicate DLLs in Win7

I'm running Windows 7 sp1 64-bit on a HP Desktop PC and I keep finding DLL files that are duplicated a dozen times or more and spread across my drive. When I do binary comparisons or checksums I usually find that most if not all of the files are identical. And why the strange path names? What happened to just sticking all the DLLs in the system path and letting all dependent programs access the same file, like in XP and prior? Here's an example where all 11 instances of NPAdbExternal.dll are 644 KB and identical by binary compare:

C:\Program Files\Security\Malware\IObit Malware Fighter\adsremoval\Firefox\adsremoval@adsremoval.net\bin\NPAdbExternal.dll
C:\Program Files (x86)\IObit\IObit Malware Fighter\adsremoval\Chrome\gkcefkcdkepgkpbgncjchhbjgoanleod\1.0.0_0\dll\NPAdbExternal.dll
C:\Program Files (x86)\IObit\IObit Malware Fighter\adsremoval\Firefox\adsremoval@adsremoval.net\bin\NPAdbExternal.dll
C:\Program Files (x86)\Secure Speed Dial\IE\ADBlock\Chrome\ojkdcodhlkmiakbangobnmdhieapagic\1.0.0_0\dll\NPAdbExternal.dll
C:\Program Files (x86)\Secure Speed Dial\IE\ADBlock\Firefox\searchads@instair.net\bin\NPAdbExternal.dll
C:\Users\owner\AppData\Local\Google\Chrome\User Data\Default\Extensions\gkcefkcdkepgkpbgncjchhbjgoanleod\1.0.0_0\dll\NPAdbExternal.dll
C:\Users\owner\AppData\Local\Google\Chrome\User Data\Default\Extensions\ojkdcodhlkmiakbangobnmdhieapagic\1.0.0_0\dll\NPAdbExternal.dll
C:\Users\owner\AppData\Roaming\Mozilla\Firefox\Profiles\bi04q69j.default-1385631510424\extensions\adsremoval@adsremoval.net\bin\NPAdbExternal.dll
C:\Users\owner\AppData\Roaming\Mozilla\Firefox\Profiles\bi04q69j.default-1385631510424\extensions\searchads@instair.net\bin\NPAdbExternal.dll
C:\Users\owner\AppData\Roaming\Mozilla\Firefox\Profiles\upbsmor9.default-1386248938622\extensions\adsremoval@adsremoval.net\bin\NPAdbExternal.dll
C:\Users\owner\AppData\Roaming\Mozilla\Firefox\Profiles\upbsmor9.default-1386248938622\extensions\searchads@instair.net\bin\NPAdbExternal.dll

When I first got Windows 7, I made the mistake of trying to clean out duplicates like this but quickly found that programs stopped working, even if an identical file was in the system path. Does anyone else run into this sort of thing on their Windows 7 systems or do I have something freaky going down on mine?

 

Those dlls are for plugins for Chrome and Firefox, looks like. Each version has to be compiled separately. In addition, you installed programs that have them available, and when the browsers enabled them, they copied the DLL to their own respective directories.

 

I still don't get why individual programs need to have their own personal copy of a DLL that already exists elsewhere on the system, especially a copy that exists in the system path. That's not the way things were in earlier versions of Windows. But, what the heck, as long as it's "normal" for Win7 to do this, I won't lose any sleep over the matter. Thanks Adrynalyne................ AGAIN

 

Actually, it was like that before too. Even worse in the 9x days.


As to why programs do this, its probably because Windows is not big on symbolic links. If it was, we would see a lot less of this.