Yes, this is very common, particularly with that retailer!
They put through a preauthorisation when you place the order, which blocks the funds on your card. Then when the order is ready for shipping, they put through the actual transaction. In theory what should happen is the actual transaction should refer to the preauthorisation and it would change he block to a hard posting.
I've read several reasons for this not happening; e.g. if your original order is shipped in separate packages they have to put through different amounts.
Where this really manifests itself is with prepaid cards, or for example Revolut as the second transaction can't post. There might be an expectation from the retailer that the block will have expired or something like that.
The usual outcome is retailer blames bank, bank blames retailer, and customer loses out waiting for the block to expire so they can access the funds.
It's a terrible customer experience. You'll find thousands of complaints about this online.
I'm not sure what you can do about it I'm afraid.