second read in pair should be filtered out in umi_joining.sh?

[ssayols]

Hi there,
I was wondering if the grep -v '\\2' in this line is meant to filter out the second read in the pair?
If this is the case, is the regex '\\2' the right one? or should it be '\/2', like the one used in the sed that appears downstream removing the tag for read 1?

thanks!