Single-worded verbs being repeated when use in a sentence
It is called verb reduplication and it is not the first time I explain it.
From my answer to another question What is the purpose of verb reduplication?

Phrases like 笑笑，看看，走走 or 吃吃 are verb reduplication, it serves to indicate the verb is in a slight degree or a casual manner

From my answer to yet another question 快把大衣穿穿！When is it wrong?

Reduplication of verb imply the verb is in 'a slight degree', 'a casual manner' or 'tentative manner'
Examples:
吃 = eat
吃吃 = (slightly/ casually) eat
试 = try
试试 = (slightly/ tentatively) try

The difference between 请数 and 请数数 is 请数 sounds like a blunt demand; 请数数 sounds less demanding (reduplicate the verb 数 hinting you make the statement in a tentative manner. Not that you are not sure the other person should count, just you are not forcefully telling him to do so)