Hi,
It's not a bug.
It's made on purchase to avoid problems with the fact that you remove the id from URLs. If HikaShop was not doing that, the 10 at the beginning would be interpreted as the id of the category and it would display another category when clicking on the link. Adding a latter at the beginning, the system ensures that this doesn't happen.
Please either deactivate the removal of ids of products/categories from URLs, or use an alias which doesn't start with a number if you want to avoid that.