Not reproducible on Linux:
$ movescu -b AET -c CALLAET@localhost:11112 -m 00100020=1234 -m 00080050=123456789 --dest DESTAET
09:18:35.627 INFO - Initiate connection from
0.0.0.0/0.0.0.0:0 to localhost:11112
09:18:35.633 INFO - Established connection Socket[addr=localhost/
127.0.0.1,port=11112,localport=55489]
09:18:35.638 DEBUG - /127.0.0.1:55489->localhost/127.0.0.1:11112(1): enter state: Sta4 - Awaiting transport connection opening to complete
09:18:35.639 INFO - AET->CALLAET(1) << A-ASSOCIATE-RQ
so I guess it's related Windows command shell - you may try to quote arguments containing '='.
Anyway, the invoked C-MOVE RQ will be not be DICOM compliant, because of the missing Study Instance UID - and you also should not include an attribute like Accession Number, which is not an unique key!