Am looking directly at the downloaded image of 1878 Births in the Burgh of Paisley, Renfrewshire. Twins, Robert and Alexander born 13 April, 1878 to William WHITE and Caroline WALLACE. I'd say the father did not remember the correct date for their marriage. Why he would report that it was Halloween [31 Oct] instead of in November, I'm not sure.
Possibly the family tree posted earlier today is from a non-confirmed source. If ages were guessed from census data, actual birth years can be way off. if ALEXANDER is the one who lived and ended up in Canada, he could not have died as the tree shows. And it also doesn't show these 21878 births. 1878 is clearly written along the top of this document and 3 different places down the side of the page.