Too many mobile phones

I am fed up with carrying two or more mobile phones with me. You know the problem, don’t you? But regarding the current technical options…

But I guess the root of all evil is marketing as every operator wants to sell branded mobile phones, to tie the customer down. But…

Just from my point of view it wouldn’t be a big deal doing a mobile phone having two sim cards inside for parallel use - having two receivers in it. If those phones would be built having up to date features, I would just carry one phone with me, which would be a phone sold less, which would result in a slowdown on sales. Another thing would be, that the ‘free and superb phone’ wouldn’t be an argument for selling a contract.

But nevertheless it would be worth a research if there are such phones available. But I doubt that there are good ones out there regarding the reasons stated above…