Those Park Avenue signed exclusives seem to be one or very few of each title, likely signed as the back comes into town, to play a show. But looks like they do a charity donation for each sold, so a good cause.
Similar to what MusicRecordShop in St. Louis was doing but seems like they've unfortunately closed for good.
You're right -- they secure a few extra copies if they can get a band to sign after they play in Orlando. If it's a well-known band, they can go quickly.
Music Record Shop was great, but they closed their brick & mortar store in 2022, and soon pivoted to becoming auctioneers and charging exorbitant prices on their website. ($130 for a signed Breaking Benjamin, for instance.) But when they charged normal (inflated, but reasonable) prices and kicked back $5 to charity on each purchase, they were the best.