So, does his Boston contract stay active and he double-dips?
Does his Vegas contract net against the Boston deal?
Does his Vegas contract supersede the Boston deal and make that deal dead?
Yes/no. The contract remains active with respect to those provisions that the contracts specify will remain active. It likely does not allow him to double-dip.
Probably.
See first answer above.
Almost all employment contracts have what are called mitigation clauses. Those provide that in the event of termination any severance payments (or in this case the balance of a guaranteed contracts) will be netted against what is paid by the new employer.
Right, and in many coaching contracts, there are provisions that would prevent the coach from taking minimal salary for the contract year and getting it made up over the remainder of the contract (a "substantial underpayment compared to market” clause). Plus, I'd expect Cassidy will be making more with VGK than BOS, given the inflation in coaching salaries since he signed his last contract with BOS.
Congrats to Cassidy, and good for BOS that he will be in the Western Conference.