Well, 1876 is correct according to the birth register of Dall parish, Aalborg county, Denmark:
http://ao.salldata.dk/osd_vis.php?bsid=356737&side=23
Skudshale is the place in Dall parish where he was born.
I think I have found the reason to the inconcistency.
Ejnar's younger brother born 11 july 1877:
Cannot be found in the birth register of Dall.
He is probably identical to the brother born 10 july 1878:
Whose birth you see here in Dall birth register:
http://ao.salldata.dk/osd_vis.php?bsid=356746&side=8