Try this approach using a helper column on sheet2 (I used W)...
copy this to W2 and copy down...
=G2&COUNTIF($G$2:G2,G2)
Then use this on sheet1 to pull in the values...
=IFERROR(INDEX(Sheet2!$R$2:$R$20,MATCH(Sheet1!F2&COUNTIF(Sheet1!$F$2:F2,Sheet1!F2),Sheet2!$W$2:$W$20,0)),"")