Yes, it's pointless to have two tags referring to the same thing. Since deepqa had three questions and watson had four (and all but one DeepQA question had the Watson tag already), I manually merged the tags together by removing deepqa.
One could make the argument that DeepQA is the research project while Watson is the product, but all of the questions tagged deepqa were about Watson.
Watson is the name of the computer, and DeepQA is the name of the technology and software. They both correlated, but Watson sounds like more specific, but on the other hand there are no any known computers which are using DeepQA which aren't called Watson.
We do not know if there are any other computers which uses DeepQA technology, but not related to Watson. There could be some implementation of DeepQA not being called Watson. To simplify things, both terms can be synonyms where watson should be the main tag, since it is more popular (it has its own Wikipedia page, where DeepQA does not).
More detailed information about the differences check @Avik post and the following answer:
I would be careful to merge the two together. deepqa is very much just that - a deep learning approach to questions and answers. This covers NLP, hypothesis formation, candidate answer generation, and answer selection from the candidates. It is fully limited to that domain.
These pages show what I'm getting at:
https://www.research.ibm.com/deepqa/deepqa.shtml http://researcher.watson.ibm.com/researcher/view_group_subpage.php?id=2159 http://researcher.watson.ibm.com/researcher/view_group_subpage.php?id=2162 http://researcher.watson.ibm.com/researcher/view_group_subpage.php?id=2160
On the other hand, watson is this titanic over-arching project that dips into culinary arts, healthcare, and more recently education and other topics I'm sure I'm missing. It is the foremost product of IBM's cognitive computing research and has numerous applications and uses, and elements that construct it. It goes well beyond just the QA portion (which is an integral part of Watson, but not the entirety or even nearly a synonym of Watson).
For this reason, I personally think they are certainly different topics, but being new to stack exchange I'm not sure how you would like to handle this.