Single conversion recievers have one image frequency.

Dual conversion has two stages of image frequencies and has better adjacent signal rejection.

The radio signal is converted down to a lower frequency for amplification.
the lesser one is 455khz I'm trying to remember the next one up but its somewhere around 1460khz.

The crystal in your reciever doesn't actually have a resonant frequency equal to the channel frequency, it differs by the image frequency.

Probably getting something started here?

Enjoy,

Jim