Partial and total concentration in solutions
It's true and false.

For example: 
1 Solution with 1mol/L of NaCl and 1mol/L of KBr.
The total concentration of salts is 2mol/L.

But the ions concentration are:

Na+ 1mol/L
K+ 1mol/L
Cl- 1mol/L
Br- 1mol/L

Is it clear?