While CARD and FORMatted are equivalent keywords in an OPEN statement, for a READ COOR statement, CARD conflicts with DYNR, as each represents a different file layout for a formatted file.
In fact, the command works fine as simply
read coor dynr curr name xxx.rst
and using the FORM keyword should give the message
**** Warning **** The following extraneous characters
were found while command processing in CHARMM