r mask for grep for finding the repeated words

You can use stringr,

str_count("HALL #1 HALL #2 HALL #3", 'HALL')>1
#[1] TRUE

You could use (?:.*?HALL.*?){2,}:

grepl("(?:.*?HALL.*?){2,}", "HALL #1 HALL #2 HALL #3")
#[1] TRUE

Here is a breakdown of the above regex.