String duplication with tripwires

place two tripwires with 3 blocks between.   Place string between the tripwires.  Flood the string with water.   This results in 4 string, instead of 3, as the center string seems to create a stack of two.

 

NOTE: this exploit has now been posted to Reddit and is public.  https://www.reddit.com/r/Minecraft/comments/razrv8/very_simple_string_duplication_glitch_118_java/