Themes representing multiple ideas or being recontextualized is not a new thing in Star Wars.
Obi-Wan's theme is also the Force theme.
Luke's theme/Main Title has Ben recontextualized as being the Main Title for the whole of Star Wars as well as becoming a theme for heroism, action, and adventure. It's prominently heard while Qui-Gon and Obi-Wan fight off droids in TPM, and as apart of "Scherzo for X-wings" in TFA.
Darth Vader's theme is also the Imperial March. It's played for Imperial forces, Star Destroyers, the clone army, even Palpatine fighting Yoda.
The March of the Droids from TPM, is repurposed as the march of the clones in AOTC. Hinting at the same driving force behind them.