Hi , it looks like you created two separate blockchain posts (two separate permlinks):
To update an existing blockchain post or comment, you have to specify the same permlink and then the chain will update the post with that permlink.
You can remove the duplicate store product by changing its status field in the json_metadata. Submit the post with the full json_metadata but change that field so it's "status": 2, i.e. inactive (as per the protocol documentation in this post). Similarly, make the price field to what you want.
It also works with comments. You can publish either a post or a comment and it will pick it up as a product, as long as the json_metadata is right.
It's a bit of a hassle currently since there is no UI support to make this easier, but hopefully it's coming soon.
RE: Hive Open Market - buy & sell products and services with crypto