VZW on the last one meant that the device is originally sold by VZW. Same with my device, it has TMB/TMB, TMB/XAA because my device is SM-N986U1 (directly unlocked from Samsung).I flashed the phone last night and everything was successful. I had the exact same results as nuprotocol where there was first an error and required a factory reset, then it rebooted with VZ for a while before saying new SIM found, then rebooted with ATT software.
Everything works perfect but I did notice in software information, under service provider software version, it says ATT/ATT/VZW. Not sure what that means but something from Verizon is still on there.