Command 'coeff' (CAS Mode)

[komame]

This problem also occurs for much simpler cases.
Assigning the expressions:
5*sin(2*x) and 5*sin(x*2) to the variables "a" and "b" results in "a" and "b" containing exactly the same expression: 5*sin(2*x).
However, applying the coeff function to each of these variables yields different results => screenshot.