Do law firms ask whether you have gotten TC offers from previous vacation schemes during AC?

I did two vacation schemes last summer but didn't get any TCs from both. Both firms are well-known for taking in a lot of VS students and that really makes me lose my confidence in applications. I am worried that if I get invited to an AC and they figure out I haven't gotten any TCs, they might think I am not capable.
 
This is a fairly common question at an interview stage, and so it is one to prepare for.

If you have got an interview though, it is reasonable they have already worked out that this is the case and by inviting you they clearly don’t care/worry about it that much.

It’s very common for people to not secure TCs from VS. Sometimes people are not matched with the right firms, sometimes they are just not ready and need some more time to develop their skills or motivations. It doesn’t mean they are a “bad” candidate - it just means the vac schemes at the time were not the right opportunity for them. But with applying to different firms and developing your skill set over time, the next TC opportunity could be the right one.