__DATA__
0024.118.3A F T TFF     
0024.118.3B F T TFF
0024.118.3C F T TFF
0024.118.3D F T TFF
0024.118.4  F F TFF

should (and does) produce the following groups

0024FT containing 0024.118.3A,B,C,D  TFF
0024FF containing 0024.118.4         TFF (coincidently)
the degree causes the change in grouping