Only one way to find out!
Personally, I would stick with bought seeds, random seeds are usually the result of a female turning hermaphrodite, meaning the seeds made this way have a genetic dominance for being hermaphroditic themselves.
Saving a few dollars by growing bag seed with unknown genetics and questionable stability, could mean spending weeks/months growing a plant that you end up chopping down early due to undesirable factors, such as hermaphroditism, making the cost many, many times higher than buying a seed from a reputable breeder.
You could grow it and see, but whatever you do, don't make it the main plant in your grow, only as a side line experiment to test it out. If it is a hermie, you don't want your whole grow to be a waste of time. Far better to grow it as an experiment, take some cuttings and if all is well, use the cuttings for your next grow. At least this way you will know if the bag seed is ok to invest all your time and effort into a serious grow.
Hope this helps,..........
Organoman.