Did you check you have same settings for recognizers? We introduced the acronyms recognizer in SP1. The release notes say this:
Studio 2014 includes some changes related to recognized tokens (also referred to as
placeables), for instance in the area of acronyms.
To ensure optimum matching and avoid creating duplicate translation units when you edit
existing 100% matches, SDL recommends that you re-index all your translation memories
to recalculate all recognized tokens.
To re-index translation memories:
- Select Translation Memories view and open your translation memory.
- Click Home tab and select Settings under the Tasks group.
- Under Performance and Tuning, select Re-index Translation Memory.
- Wait for the process to finish as this may take a while.
If for any reason you are still seeing matching issues and/or unwanted translation unit
duplicates, consider exporting/importing the translation units into a new TM.
In addition to that some of the matching strategies were changed as customers reported issues that some of the matches were too high.
Without isolated files it's difficult to say anything more than this.