Modulo 2/XOR 1+1=0 Binary OR/AND 1+1=1 Binary 1+1=10 Golden mean base 1+1=10.01 Balanced ternary 1+1=11 Negabinary 1+1=110 Binary i-1 base 1+1=1100 Decimal 1+1=2 Biology 1+1=3 to many String literal "1"+"1"="11" (concatenation)
There are also films, companies and many other things called one plus one or one and one.