@DuetUser I'm using nema17 and nema24 motors on few duet's and even on the PRC clones I don't see these issues not on 1.5A nor on 2A ...
you are probably using bad cables (I had similar issues on some printers that came with iron and aluminium instead of copper cables, they just had a super thin layer of copper on them)
you are for sure using either bad connectors or you crimped the connectors poorly. Even PRC connectors when crimped properly do not heat up at 2A, but even a high end connector, if you do not crimp it properly, will create issues, heat up and everything will go to ^#$%^$ ... if you are using those %$#@^ PRC cables the crimps on them can deteriorate over time (dunno if alu moves more due to heat or ..)