Apparently things have changed.
I found this on the DLR website:
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If I buy something while I'm at a theme park, do I have to carry it around all day?
The
Disneyland Resort offers a Package Check Service. If you are staying at one of the Disneyland Resort Hotels, you may have your purchases sent directly to the Hotel. If you are just here for the day or are staying at a non-Disney hotel, you may check your purchases until you leave at:
Fly 'n' Buy in Disney California Adventure Park
Newsstand at Disneyland Park
The Star Trader at Disneyland Park
Pioneer Mercantile at Disneyland Park
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This sound like you have to take your packages to whichever place you choose and check them in yourself.
The Newsstand is the place I mentioned, just inside the entrance.