Can the Amazon US store and CA store with the same Seller ID link to different BQool accounts? 

For example: 

US Store with Seller ID 123 gets registered under BQool account A,  while CA Store with Seller ID 123 gets registered under BQool Account B. 

The answer is no. 

When the system notifies the user that a certain marketplace has an existing BQool account, the system will use the Seller ID to determine whether it exists on another BQool account or not instead of the marketplace. 

Essentially, one Seller ID can only be tied with one marketplace. With this in mind, if a user already has one Seller ID tied with one BQool account, the user can only add on other marketplaces under the same BQool account.