Every item in the pricebook has a FLEX (local) or CORE (HQ) attribute. Core items are identified with a lock symbol next to them. These items are part of the HQ pricebook and are in all franchisee pricebooks with set attributes that cannot be edited. Flex items are local items that are in your local S2K pricebook and you can edit all attributes as needed.
HQ adds new CORE items to the pricebook all the time. If you already have a local flex item in your pricebook, and HQ adds it as a core item, then your flex item will convert to a core item. This means that the attributes may change to match HQ and will get a lock symbol on it. NOTE: All history will remain for this item, just the attributes will be updated. This merge of flex to core happens every hour so for less than an hour you may see the item in your pricebook twice, once as a core and once as a flex. Within the hour the items will auto merge into the new core item and attributes.