at this time i have a lowrance x135 on my console, and want to get a bow mounted fish finder. if i buy a humminbird or eagle will the transducers mess each other up? also if i buy another x135 or x125 will those interfere with each other?

One transducer can interfere with the other, regardless of brand. How much it does depends on where they are mounted and other conditions.

Usually if I'm getting feedback from one, I just turn off the one I'm not using.