Not sure why the difference. Are you doing an IUI, or IVF? I just completed a fresh IVF cycle and used only one Ovidrel trigger shot. My eggs were mature and just fine when they went into retrieve.
I did an IUI. The Doc said my estridol was over 900 and so she only had me take one, but I don't know what that has to do with anything. Did you try IUI first?