For as far back as I can remember, my contact list has always been a disaster. I've tried several times to get things back in order but it never really seems to work out so in the end, I just give up trying. As long as the contacts I need can be found I'm perfectly fine with that. At this point, it's hard to say where the problem comes from because it's not 'just a BlackBerry thing' for me.
It happens across all platforms. That leads me to think it's Gmail but that's just a wild guess. In one last ditch effort to get things sorted out, I grabbed Contact X from BlackBerry World for my BlackBerry Z10 after reading about it in the CrackBerry Forums, to see if it would help in any sort of way. Much to my surprise, it cleaned up quite a few of my contacts and saved me a lot of hassle thanks to some superbly implemented features:
Import Contacts: all the contacts on the device will be backup to the VFC file type that is supported by Google Contacts and Outlook.
Export Contacts: From VFC file, user can export to the contacts on the device.
Merge Contacts: application will find duplicated contacts, then user can choice merge by phone or by name (Contact X work with local contacts, SIM Contacts and contacts are synchronized with email account (support CardDAV).
Delete all Contacts: Remove all the contacts off the device, be careful with this function.
The feature I used specifically was the merging of contacts. Sure, I could have gone through and done it all manually but that's a huge pain in the ass and let's be honest - I'm lazy at times. In the end though, Contact X managed to find all my contacts that had been mismatched and merged them all for me, subsequently reducing my train wreck of a contact list down to 77 well organized entries. I'm not going to say it will work as good for everyone as it did me but for the price of the app, it's certainly worth a shot.
Learn more / Purchase Contact X