When G5 started shipping, my guess is that they shipped 2 transmitters to match 6 month G4 transmitter life/warranty. Both G4 and G5 used same sensors.
My first shipment of G6 transmitter from DME in 2019, I was mad that they sent 2 transmitter. It means the 2nd one drains slightly (at least 3 months), unlike the G4s which could preserve battery until removed from package. So seems to vary by supplier, and may do 2 G6s based on how it was set up in their system.
Fortunately in 2020, I switched to filling from Costco (since insurance switched to new PBM), and now get every 90 days as pharmacy, which delivers 1 day after refill request, or same day if called in early enough. I’m hoping this gets me a “fresher” transmitter, not one sitting around in warehouse (or home), draining battery.