Yes it is odd, however i have been told on may occasion, that many documents had spelling errors and some how we have to work out the correct info ourselves from info gathered. This has been true in most cases i have researched so far.

For example.. an aunt and uncle were listed as being born 1810 and 1815 on one census, then the next census they are listed as being born 1820 and 1825 ! It was explained to me that if the wife was at home during the taking of the census, then that's probably the reason for errors on dates. As most couples were not 100% sure of their spouses true date of birth :-)