If you can still primer sealer around the primer pocket it's probably once fired.
That said, I wouldn't worry too much about how many times it was fired. If the primer pockets are still tight and you can feel no groove above the web of the case using the bent paperclip technique I wouldn't see a problem reloading them. By the way, you should check for the groove AFTER resizing.
Consider that depending on things like chamber versus sizing die die dimensions, pressures generated in the cartridge, etc., some cases can go 20+ reloadings before they're no good.
