Duplicate vowels with delrel=0?

[Cielbird]

I am using the ipa_bases.csv file, and while parsing it I noticed that some vowels (from line 116 to 121) have duplicates, with only one difference: the delayed release column is '0' instead of '-'. This doesn't make sense to me, since how would a vowel have a delayed release? However, I am new to the concept of distinctive features, so maybe I am missing something.

[dmort27]

This is a bug. I will fix it when it is possible for me to do so.