You're going to need to provide rather more details (e.g., WTF is the -9?). Also, what have you tried?

This lgen file format:

100 100 rs2236941 A A

100 100 rs2236985 G G

100 100 rs2237142 C C

100 100 rs2237162 A G

100 100 rs2237175 A G

and this is ped file format:

100 100 0 0 -9 A A G G C C A G A G

I try to use plink --lfile Plate3_final_report --recode

But I got error:

Duplicate ID '100 100'