Started to put it back together

I’ve not touched it since about November but now with the warmer weather I’ve started to put it back together.
Just a minor problem with a nut on the exhaust manifold. As I started to tighten it, it started to spin and wouldn’t come back off. I remembered when dismantled it this stud was missing a nut. So I suspect someone had had a problem with it previously. I added a second nut on top and was satisfied as I didn’t want to replace the studs.
Then I remembered that I’d used the wrong sealant on the exhaust manifold gasket. So I had to take it back off. Remember that spinning nut? Now it won’t come off. So I have to cut it off and I have some new studs on order. At least I have a use for the stud removing tool I inherited 10 years ago and so far haven’t used.