Despite the code being identical other than the ordering of the "addEventListener" calls, the results change when run on the Cloudflare Worker platform.

1.js

addEventListener('fetch', event => {
  console.log("fetch handler 2", event.request)
})

addEventListener('fetch', event => {
  console.log("fetch handler 1")
  event.respondWith(handleRequest(event.request))
})

/**
 * Fetch and log a given request object
 * @param {Request} request
 */
async function handleRequest(request) {
  console.log('Got request', request)
  const response = await fetch(request)
  console.log('Got response', response)
  return response
}

/**
Outputs the following:

worker.js:2 fetch handler 2 Request {…}
worker.js:6 fetch handler 1
worker.js:16 Got request Request {…}
worker.js:18 Got response Response {…}

**/

2.js

addEventListener('fetch', event => {
  console.log("fetch handler 1")
  event.respondWith(handleRequest(event.request))
})

addEventListener('fetch', event => {
  console.log("fetch handler 2", event.request)
})

/**
 * Fetch and log a given request object
 * @param {Request} request
 */
async function handleRequest(request) {
  console.log('Got request', request)
  const response = await fetch(request)
  console.log('Got response', response)
  return response
}

/**
Outputs the following:

worker.js:6 fetch handler 1
worker.js:15 Got request Request {…}
worker.js:17 Got response Response {…}

**/

Apparently the cloudflare worker platform only executes 'fetch' event handlers until event.respondWith is called