#!/usr/bin/env gawk

BEGIN { OFS="\t" }

NF { count[$1]=++count[$1]
     rec[$1][count[$1]]=$2 }

END {
    for (head in rec) 
		for (i=1; i<length(rec[head]); i++) 
			for (j=i+1; j<=length(rec[head]); j++) 
				print head, rec[head][i], rec[head][j] }