The TPXL0706 messages mean the specified request made to CA-L-Serv has failed. The file DDname is given if the request applies to a specific file (This is not a CA-L-Serv initialize or terminate request).
See the CA-L-Serv portion of the CA Common Services guides and the VSAM guides to determine the correct action based on the codes you receive.
The MRGVRED message means that, at the time that user was signing on to CA TPX and CA TPX attempted to write out the ADMIN2 record for this saved dynamic user, someone had that user's record open in TPXADMIN and therefore, the record was 'locked' and could not be updated.
It's also possible that this user had already logged off and not displayable in TPXOPER. VSAM updates are CI based and a CI can hold several user records. There is nothing that can be done to avoid this from CA TPX perspective.