Installing several mods

[kia]

Hi. I'm trying to install several mods. When I copy them there are files like "customization_items.xtbl" and
"customize_item.asm_pc" that are more than one. If I replace them the previous mod wont work how do I install them ? How should I merge them ?

 

[Quantum]

You can't use two mods that both have the same file at the same time without merging mods.
To learn how to merge mods, read this tutorial for Saints Row IV, which mostly applies to Saints Row 3 except you'll need to use the Saints Row 3 modding tools:
https://www.saintsrowmods.com/forum/threads/merging-mods-many-images-within.4782/