Checking whether you have cited some other researcher
If you are fine with looking at only Web of Science indexed articles then yes, this is easily possible using Web of Science.


Do a "Cited Reference Search" and search for the name of the researcher you are interested in
Select the publication of that researcher and hit "Finish Search", you now end up with a list of every paper citing the previously selected papers of that researcher
Do a basic author search of your own name, you end up with a list of your own papers.
Go to "Search History" and select these two searches and combine the two sets with the "AND" operator.


There's another way to do this using Web of Science. It will take some time and work to set up (depending on how many publications you have) but the process of checking can be automated afterwards. You have to create a list of all papers you cited which includes the author names of the cited papers.


Search for your publications on Web of science
For each publication open the details, on the right it shows the number of "Cited references", click on that number you end up with a list of papers you cited
Export this list to endnote (you have to do this for every page)
Eliminate duplicates in Endnote.


You now have an Endnote database with all the publications you cited which can easily be searched for authors.