Not necessarily. Ideally, it should be similar, but the salary, both as an employee and as a member of the board, may vary each month. That is, you do not need to always assign the same salary.
We recommend you to write a employment contract for yourself in which you specify a base salary and a variable productivity bonus. For example, imagine that some months you can only pay yourself 1000€, but others you have enough income, which allows you to allocate up to € 500 salary.
In that case you could specify a base salary of 1000€ per month, plus a variable productivity bonus of € 500.