OK,

the way I look at it is that:

the only galaxies we have seen are ones that are very very far away, we have never seen our own *because we are in it*. So when we look at a galaxie far away, the distance between the back end and the front of the galaxie is so insignificant compared to the distance the light has to travel to get here that we can't differenciate between the light from the front and the oh so slightly old light from the back. PLUS, when you see the spiral of a galaxie, its like watching a flat object so there is no back and front end, do you get it. Lokking at it from the side looks like a line. and even then you still can't tell front from back. So this intire question really is pointless.

NOW, if we were to take pictures of our own galaxie... maybe we could encounter such an issue since the ratio of the size of the galaxie vs how far ithe light is going to travel is way smaller.

My grain of salt.