Is it normal for the inside of one testicle to go back farther than other?

It is normal for one testicle to be located slightly higher or lower than the other. The testicles are suspended in the scrotum by the spermatic cord, which allows them to move freely. This movement is important for regulating the temperature of the testicles, which need to be kept slightly cooler than body temperature in order to produce sperm.

If you are concerned about the size or position of your testicles, you should see a doctor.