It would actually add to the issue also, as you are essentially always at some point switching to one which is not as effective.
Im interested as to whether or not you upped the sensitivity on hCAPTCHA? I ask as thats tended to be effective in most cases I have tried.
Of course, adding additional measures as you have mentioned there is never going to hurt, and glad you managed to get the issue resolved for yourself. In your case, you found you did need extra, however you had also made sure things were set up correctly first of all. My point above was that in many cases (most) we find they havent been. So its always advisable to do that in the first instance.
Of course feel free to post that up as a suggestion in our feedback area, as mentioned 🙂