Rather than trying to do something with the existing test results, just run new test cases and filter your output:

prove -rl --formatter=TAP::Formatter::JUnit --timer t/| tee junit.xml
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)