i have seen this also

For me it has been a rare occurrence.  The multiple dip. requests pop quickly up with the second overwriting the first , so there is no viable screen shot to capture,  Yuo would have to be recording the whole game when the random 2 diplo requests show up

Next time I see this, I will send you an autosave.  Like the others, it's a rare occurence and recording it is kinda impossible unless I record the whole game.  Due to the random nature of diplomacy though, it will be hard to reproduce (I could not, personally, but maybe you have ways to "force" it).