So I'm a little confused- I am pricing flights for a trip home to N.Ireland for my brother-in-laws wedding in June 2012.

If I go onto KLM website flying from Dublin-Amsterdam-Calgary... for 2 adults, 1 child and an infant we can fly for 1252 GBP ($1965 CAD)

If I go onto KLM Website (change the country to Canada...as this is the only way I can type in a canadian airport) flying from Calgary-Amsterdam-Dublin... for 2 adults, 1 child and an infant they are charging 3526 GBP ($5538 CAD) !!!!

This is working out over twice the price and I'm curious to know why and is there any way around this?

Telephone. Use the telephone to establish a channel of direct communication with KLM in Dublin. Ask them, verbally, what price they would charge for the flight you want. If their price doesn't suit you telephone the Dublin office of another airline. By using the telephone you escape the preconceptions of the website designer and can experiment with an innovative approaches, for example, the person at the other end may suggest going via a different route. The technology is really neat, you don't even have to be able to type.

Well time machines are expensive so it's to be expected.

Seriously though, also try third party websites such as Expedia, Travelocity. However if you're talking June 2013 (and not 2012) then it's more than six months away so you're only going to get basic high end pricing.