About the potential add-on job:
Is it a set amount of work in a specific time frame?
Or do you only take on as much as you want to?
If so, can that vary (as in can you take less when not up to it)?
If you realized it was too much and needed to quit, would it be a big deal? (What kind of committment is expected?)
Do you need the money?

In regards to trying to balance the potential job with the current:
If they found out would they likely fire you?
If that happened, how problematic would that be for you? (Income, benefits)
Would losing current job make it difficult finding another in your field?
If the field didn't matter, do you have skills for others that are viable?
How tough is the job market there?
If you didn't work on it during current job hours, would you have enough other time available?

You don't have to answer all these here if you don't want of course, but they are the kinds of questions you should consider. When we're going hypo/manic, we don't tend to see downsides and consequences, so those are important to think about and discuss.

I'm not saying you should take it (especially I can't get past the double time thing)or not. I think you should be checking in with you pdoc, because yes, you do seem a bit elevated. I throw the questions out there because, for me at least, once I get an idea and put it out there, I'm highly likely to proceed without thinking much more. Especially about consequences. Just something to maybe put the reality brakes on in case it is that way for you too.