Butternut Squash doesn't look like a BNS

Hi, I am growing a BNS in a large planter on my patio (i haven't a garden but hope to get an allotment by the end of the year).  To begin with I only had female flowers (with a miniature bns behind them) and no noticeable male flowers.  I now have two squashes about 7 inches long that don't look like bns's (I used to grow them on my previous allotment) and quite a few male flowers.  The squashes are oval in shape and have green and yellow marbled skin, any ideas?  I bought the plant as a seedling from a garden centre.