After a short research i discoverd that the Doctor64 and Z64 Backup units were not able to handle the special 16KB EEPROM (Unlike my superior CD64 which i have fully fixed btw

) so a crack was written in order to convert the EEPROM to the 128KB SRAM, and this save was written for the cracked rom of DK64, so this is in fact a SRAM save. Unfortunatly for you PJ64 does emulate the 16KB EEPROM thus making this save uncompatible.
Your
Only option is to try cracking the rom and then changing the RDB to use SRAM, but that is very unlikely to work.
have a nice day.