1+1=2 does not always apply in the universe as there are plenty of cases in the real world where the total is more then the sum of it's parts.
I think I understand what you are saying, but your description can be confusing.
It's not that 1+1 = 3.
It more like if we say 1 object plus another object is 2. And then the subsets of that object each add up to say 1000 parts.
So 1+1 = 2
And consecutively 1000+1000=2000
And logically it would follow that 1000 = 1 since the subsets of the set represent the same thing as the 1 represents.
Yes I think this problem arises from the fractional system how it's represented in the decimal base system.
This is why said a binary number system is more efficient. Fractions could be represented as probabilities, and easily added up, and they always equal 1 in total.