Remove duplicated error

stevecheckoway · jgraham · commit 6030cb6e40a0 · 2021-07-05T14:17:18.000+01:00
This error line appears to have been duplicated by mistake.
diff --git a/tree-construction/tests19.dat b/tree-construction/tests19.dat
@@ -1015,7 +1015,6 @@
 <!doctype html><p><math></p>a
 #errors
 (1,28): unexpected-end-tag
-(1,28): unexpected-end-tag
 #document
 | <!DOCTYPE html>
 | <html>
