Schedule D double counting ST & LT gains

Form 1099-B was downloaded from Vanguard into Turbo Tax.  TT generated a form 8949 and entered results on Schedule D Lines 1b & 8b.  TT also entered the same numbers on Lines 1a & 8a and totaled the two making the results double what they should be.  How can I remove the entries from Lines 1a & 8a so the total will be correct?