Yes, all 4 can be redeemed at one time or split up over multiple subs, choice is yours. Just know these vouchers are for regular tier subs. Cannot be applied to any variety or expedited tiers. PCGS has these details on their site.
Be aware of significant delay at PCGS. I did 8 club vouchers and got verification on November 12th that they received my coins. Still waiting for the grading results. I sent them a note. The response was they require 30 business days. I checked a week ago and that 30 days is now posted on their website at 60 business days for return on grading. Something is up.