Duplicate a highlighted clip and its track, rename track with B, C, D, etc

Hey @Jonathan_Grossman, nice script!

Give this a try. Cleaned it up a bit but kept your commentary:

//This script duplicates a selected track (eg.Track 1), then renames the duplicate "Track 4B" then "Track 4C" etc.
//Note: This should be assigned to a keyboard shortcut or Stream Deck button.

function duplicateSelectedTrack() {
    sf.ui.proTools.trackDuplicateSelected({
        duplicateActivePlaylist: false,
        duplicateAlternatePlaylists: true,
        duplicateAutomation: true,
    });
}

function separateClip() {
    sf.ui.proTools.menuClick({ menuPath: ['Edit', 'Separate Clip', 'At Selection'] });
}

function copyClip() {
    sf.ui.proTools.menuClick({ menuPath: ['Edit', 'Copy'] });
}

function pasteClip() {
    sf.ui.proTools.menuClick({ menuPath: ['Edit', 'Paste'] });
}

function muteClip() {
    sf.ui.proTools.menuClick({ menuPath: ['Edit', 'Mute Clips'] });
}

function unmuteClip() {
    sf.ui.proTools.menuClick({ menuPath: ['Edit', 'Unmute Clips'] });
}

function renameFunction(trackName) {
    //This function gets called after the Rename track dialog is open
    //the argument 'trackName' holds the existing name, eg. "Audio B.dup1"
    //We're supposed to eventually return the target name we want from this function.

    /** @param {{ name?: string, letter?: string, oldName?: string }} args */
    function getNewName({ name, letter, oldName }) {
        let newLetter;

        if (oldName) {
            name = oldName.slice(0, -1);
            newLetter = getNewLetter({ oldLetter: oldName.slice(-1) });
        } else {
            newLetter = getNewLetter({ oldLetter: letter });
        }

        const newName = name + newLetter;

        return validateName(newName);
    }

    function getNewLetter({ oldLetter }) {
        const letters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';

        if (!oldLetter) return letters[1];

        let oldLetterIndex = letters.indexOf(oldLetter.toUpperCase()); //Find the index (0-based)
        let newLetterIndex = ++oldLetterIndex; //Set to the found index + 1

        if (newLetterIndex >= letters.length) {
            throw 'All letters have been used.'; //We reached Z or some other error
        }

        let newLetter = letters[newLetterIndex];

        if (oldLetter.toLowerCase() === oldLetter) {
            newLetter = newLetter.toLowerCase(); //Make letter lowercase if the input was lowercase
        }

        return newLetter;
    }

    const validateName = function () {
        const namesOfAllTracksInSession = sf.ui.proTools.tracks.names;

        return (name) => {
            function isThereATrackThatStartsWith(name) { // Prevents conflicts with playlist
                return namesOfAllTracksInSession.some(trackName => trackName.startsWith(name))
            }

            if (isThereATrackThatStartsWith(name)) {
                return getNewName({ oldName: name });
            } else {
                return name;
            }
        }
    }();

    var grps = trackName.match(/^(.*)([ \d])([a-zA-Z])(\.dup.*)$/);

    //This regular expression matches a string containing of the following groups (each group is in parentheses)
    //Group 1 - syntax: (.*) - meaning: Match any number (*) of any characters (.) This will match "Audio"
    //Group 2 - syntax: ([ \d]) - meaning: Match a space ( ) or a number (\d)
    //Group 3 - syntax: ([a-zA-Z]) - meaning: Match 1 character that is a letter. This will match "B"
    //After last group- syntax: \.dup.* - meaning: Match a dot (\.), the text "dup", and then ANY character (.), any number of times (*)

    let baseName, spaceOrNumber, letter;

    if (grps) { // Match
        [, baseName, spaceOrNumber, letter] = grps; // Destructuring relevant group matches
    } else { // No Match
        baseName = trackName.substring(0, trackName.indexOf('.dup')).trim(); //Get the base name before any .dup
        spaceOrNumber = baseName.match(/.* \d+/) ? "" : " "; // If baseName ends in a space and a number return empty string, else return space.
    }

    const newName = getNewName({ name: baseName + spaceOrNumber, letter });

    return newName;
}

function duplicateAndRename() {
    duplicateSelectedTrack();

    sf.ui.proTools.selectedTrack.trackRename({
        renameFunction
    });
}

function main() {
    sf.ui.proTools.appActivateMainWindow();
    sf.ui.proTools.mainWindow.invalidate();

    if (sf.ui.proTools.selectedTrackCount !== 1) {
        throw 'Make sure that one track is selected.';
    }

    const isAClipSelected = sf.ui.proTools.getMenuItem('Edit', 'Trim Clip').isEnabled;
    const isSelectedClipMuted = sf.ui.proTools.getMenuItem('Edit', 'Unmute Clips').isEnabled;

    if (isAClipSelected) {
        isSelectedClipMuted ? unmuteClip() : separateClip();
        copyClip();
        muteClip();
    }

    duplicateAndRename();

    if (isAClipSelected) pasteClip();
}

main();

Thank you! This works almost perfectly! A tweak if I may ask....it fails if I reselect the now muted clip on the original track, in order to make another copy of the same thing (for alternate mix options).

Also just noticed that if I attempt this with a track that has a duplicated playlist with ".01" in the suffix, it fails as well.

@Jonathan_Grossman, got em! Updated the script above.
Give it another go!

BAMMO!!! Thanks Raphael. Works perfectly now.