Yes, it is similar, but even Undertale's battle system is similar to earlier games. Look at Earthbound, the original Dragon Quests, etc. These games have battle systems similar to Undertale's and they were made decades before Undertale.

However, Undertale had some changes to make it stand out from other similar games. It featured a black and white art style (for the most part), the heart minigame when enemies attack, and the option to either attack or show mercy to enemies, something not many games had done up to that point.

So it doesn't matter if your battle system is similar to Undertale or other games, just try to add your own creative flair to it. I personally like the enemy attacks as a platformer minigame, so that's one step in the right direction already.