Using drop ship POs from our sales orders, the same 4 skus create 1 PO on some sales orders but create 2 POs on other sales others, seemingly same setup on the skus, not sure what is causing the 2 scenarios or NetSuite to split the PO in some instances? Any idea what we're obviously overlooking?

Was it you who created these transactions? If not, you may want to check if the 2nd PO was created after saving the SO. That'll create a new PO even if the same Vendor.