Recombinant DNA - Problems with ligation (Mar/04/2005 )

I am enrolled in a biotech lab 1 course at a local college. For the past 2 weeks we have been conducting experiments on cloning and selection of dna fragments. We used a pUC19 vector and the human follistatin fragment. After all the steps of gel isolating, transformation, digesting and ligation my final gel analysis revealed 2 fragments. The professor said I had a 250bp fragment and another fragment that was a "double insertion".
Why did this occur? Was it during ligation with the ligase where 2 copies of my hfs recombined together? Did it occur afer the digestion with Pst1? I don't know how to make a linear map because I can't figure out what happened. I would appreciate your input!

You need to tell us what restriction enzymes you used to cut the insert and vector so we know what was supposed to happen.