Two guitars Simultaneously through one Kemper?

This is not for gigging or anything. Just for noodling with friends.
I tried it with a simple splitter before the input and the guitars sounded like they canceled each other.

I would like for both guitars to have use of the same rig and effects as the other.
Not trying to give each its own settings as I am sure this would be impossible.

So a simple mixer before the Kemper input from the guitar. Ok.

This is just for rare occasions when a friend comes over and we want to fart around back and forth.
Kind of a spur of the moment thing. Nothing serious of course.

I was also curious of the mechanics of why it sounded like one would cancel out the other.

I guess I could keep one of those old fashioned amp thingies around but my music room is small.
Guitar collection keeps growing but the room ain't getting no bigger.

As a matter of fact I have my first Telecaster coming Tuesday. American Standard.
I am pretty excited as most of my guitars have been too hot for me to really play classic rock and all.

Thanks for all of the advice.

Good Teli rigs?

It is a simple Y cable.
2 monos in - 1 mono out