I'm going to come at this from a UK perspective and widen slightly on investment in general and not just incubators.
I'm also going to perhaps speak from the "ideal" point of view, which i appreciate for cash-strapped start-ups isn't always the reality.
But getting investment is like a marriage. It's about two parties seeing if they both want to work together. You need to be confident that they're also right for you.
VCs will often ask who else you're talking to. And in my view you'd be mad when asked to say no-one else as this suggests:
1 you're lying; or
2 if no one else is talking to you, have they over-estimated your product; or
3 a lack of drive and commercial acumen. If you're only talking to one VC you really aren't making enough effort.
Appreciate incubators may be different, but all the same, think this stacks up in wider investment discussions.
Hope all goes well for you!