There are currently separate tags for "tor-browser-bundle" and "tbb". I've edited posts with the tbb tag to reference tor-browser-buldle instead.
Can "tbb" be merged into "tor-browser-bundle" by somebody?
There is already a synonym proposal for these two tags on the tag page. When a net total of 4 users vote for the synonym it will be automatically approved. Users who have more than 5 reputation points earned related to that tag can vote on the proposal.