Every employee reinstated for the period for which he was suspended, discharged or improperly laid off shall receive full compensation for such period notwithstanding the fact that any person was employed to perform any duties of such employee during the time of such suspension, discharge or layoff. For purposes of this Section 11b, full compensation shall mean compensation such suspended, discharged or laid off employee would have earned in the position classification during the period of suspension, discharge or layoff less amounts earned by the employee from any other source and unemployment compensation payments received during such period.