#!/bin/bash

inarray() { local n=$1 h; shift; for h; do [[ $n = "$h" ]] && return; done; return 1; } # Usage: inarray "$value" "${array[@]}"

files=("test" "foo" "foo" "bar" "test")

for filename in "${files[@]}"; do
    if ! inarray "$filename" "${files[@]}"; then
        filelist+="$filename""1"
    else
        filelist+="$filename"
    fi
done

echo "${filelist[*]}"