diff --git a/src/nf_modules/kb/main.nf b/src/nf_modules/kb/main.nf
index 9e4cfec24366f1e01add17a5738e4ec0d2ff44fb..7c0de279babd28042aeec67d7d5b2ff610c7110a 100644
--- a/src/nf_modules/kb/main.nf
+++ b/src/nf_modules/kb/main.nf
@@ -37,8 +37,8 @@ process tr2g {
   script:
   """
   t2g.py --gtf ${gtf}
-  sort -u t2g_dup.txt > t2g.txt
-  rm t2g_dup.txt
+  sort -k1u t2g_dup.txt > t2g.txt
+  cp t2g.txt t2g.txt.back
   """
 }