Split Ring Cancels From Small P.o.

Is there a list or registry for split ring cancels for Ontario.
Some of these P.O. were so small they were run from a farm house and they very rarely used their cancel with the exception of registered mail.
Three of them are within a seven mile radius. Two of the postmasters were brothers that lived a just a few concessions apart.
I've got to believe these are not that common but do people even collect less common cancels?
Sorry about the newbie questions.

Cheers, Bill

If you are member of the Postal History Society of Canada you will have access to the on line catalogue of cancels. Definitely worth the price of membership.
Additionally, there is a book ONTARIO BROKEN CIRCLES by W. Bruce Graham and edited by David Handelman that is the fore runner and basis of the PHSC website listing.
Both of these are sources of useful information. Be careful - collecting postal markings can be addictive!
GJP

To echo gporth, membership in the Postal History Society of Canada provides a cornucopia of research and information. And it is cheap. e-mail membership is only $15. .