Copy / pasting keys of multiple objects

hi there,

ive noticed that when i select multiple objects that have individual keys on the same frame,
i cant do the simple copy / paste to a different frame in the timeline, or dope sheet for that matter.
(they all jump to the 1st object location or whatever messed up)

previously when working with rigged characters, i can do that in pose modes no problem,
(wouldve been a disaster if i had to copy paste every controller separately just to duplicate a pose)

theres gotta be a solution to this, please help me or animators like me would cry :joy::joy::joy:
(im using the offical 2.8)

thank you for your time

How to do this?