that is usually how OP_Return outputs look like, they insert a certain type of "data" into bitcoin blockchain that sometimes has a certain purpose so it starts with the same bytes. sometimes it is just concatenated bytes and sometimes it is a full script that could be run. for example someone posted this 2 days ago: https://bitcointalk.org/index.php?topic=5179450.0
other than that i don't think anybody can give you any more information unless you also post the transaction IDs.
also i don't see how you think this has anything to do with reusing k values for ECDSA (which is i assume what you meant by "repeated R"). can you explain why you think that? have you checked their signature and saw the same R being repeated?