UA Feats – Would Expertise (thief tool) and Burglar combine to x4?

@stuartlitjenI always love the design notes we get in UA. Q: Would Expertise (thief tool) and Burglar combine to x4? I think x3 is more fair yeah, I'd keep it at x3

— (((Mike Mearls))) (@mikemearls) June 6, 2016

@mikemearls Does as Rogue with Expertise in thieves' tools have quadruple proficiency with them when they take Burglar feat?

— Tomer Abramovici (@BudgetCommander) June 6, 2016

I'd run it as x3. https://t.co/M6UaOn9yyf

— (((Mike Mearls))) (@mikemearls) June 6, 2016