It could be a number of problems that you will have to check to eliminate each one before you get to the bottom of it. Your printer heads could be out of line, it could be as easy as the heads need to be cleaned, although my Canon always does that automatically, (and wastes ink in the process).
It could be your driver. Where did you get the driver from. My Canon driver I had to get from the austrailia canon website. although Linux mint did provide a driver that worked called gutenprint.
After checking your head alignment which it sounds like if it's printing in double, if that don't solve your problem. Then delete the canon driver. and use the linux driver that came with the OS. GEt rid of the canon driver, restart so its starting from scratch, then go as if you were installing the printer for the first time, make sure the printer is on, and it should give you a choice of installing gutenprint.
See if that helps..
PSU: Corsair 400 Watt
Motherboard: Gigabyte EP45-UD3P Rev. 1.6 FE BIOS
CPU: Intel Core2Quad Q8400 2.66 GHz.
Memory: GSkill: 4 X 1GB DDR2 800 MHz.
GPU: PCI-E 3 NVidia GEFORCE GTX 650 DDR 5, 1GB Ram