[curiouscat]

When someone says he has a solution containing 0.1 M NaCl & 0.1 M KBr does it equivalently mean the solution could be described as containing 0.1 M KCl & 0.1 M NaBr?

i.e. In solutions is the conc. of the ions themselves the only canonical description?

[Dan]

Yes, they would be identical. I suppose the way it is written refers to the actual salts used to make up the solution.

[Corribus]

When someone says he has a solution containing 0.1 M NaCl & 0.1 M KBr does it equivalently mean the solution could be described as containing 0.1 M KCl & 0.1 M NaBr?

Although it is generally understood what this means, it's technically incorrect - you actually have no (or very little) NaCl or KBr (or KCl or NaBr) in solution. What you have is 0.1 M K⁺, 0.1 M Cl^-, etc. But this would be linguistically cumbersome. So, I think your equivalence holds, at least as far as conventional semantics goes. Obviously this becomes more problematic for salts with limited solubility, e.g., AgCl instead of NaCl.