According to the Maharal in Ohr Chadash, the word “and” is used – as in English – in a list to indicate the final item listed. In this case, there is an “and” on both the fifth and seventh chamberlain. The Maharal writes that this is due to the fact that it was customary for Persian kings to have either five chamberlains or seven at their command at one time. The list could have ended at the fifth, or (as it does in our case) at the seventh. Either one would be a “final” of members listed. Seemingly, to stoke his own ego, Achashverosh took all precautions and used all the servants at his disposal for the purpose of self-aggrandizement.