You got excited then got in a hurry, didn't you?
Bites you in the ass every time.
Approach the second one the same as the first, always.
Sorry for your troubles.
I would use a MAPP gas torch, and heat the stud red hot , then cool with PB Blaster. Do this three times at least.
Then twist with Vise Grips. Make sure the Vise Grips are on there as tight as your hands can make them the FIRST time.
Using the hammer tap on the end of the stud while twisting...