Duplicate files in .*proj files

dupes.js

var proj = ``;

const pattern = /\s*<Content Include="(.*)" \/>/;

const testing = proj.split("\n");
const matches = [];
testing.forEach((str) => {
    if (str.match(pattern)) {
        if (matches.find((match) => match === str)) {
            console.log("Duplicate found: " + str);
        }
        matches.push(str);
    }
});
console.log(matches.length === 0 ? "No matches found" : "Finished searching");