char = "LÍNEA"
char2 = "LÍNEA"

char == char2
[1] TRUE

sub_utf8 <- function(char) {
    while(TRUE) {
        utf <- str_match(char, '\&\#([0-9]+)\;')[,2]
        if (is.na(utf)) break()
        char <- str_replace(char, '\&\#([0-9]+)\;', intToUtf8(utf))
    }
    return(char)
}

char = "L&#205;NEA"
char2 = "LÍNEA"
sub_utf8(char) == char2
[1] TRUE

char3 = "L&#205;NE&#100;A"
sub_utf8(char3)
[1] "LÍNEdA"