ruby heroku のデプロイでFailed to install gems via Bundler.とエラーが出ます。

herokuのデプロイでgit push heroku masterを入力するとFailed to install gems via Bundler.のところが赤字でエラーが出ます。

いろいろ調べたところbundlerのバージョンを変えないとダメとあったので、
bundlerのversionも2.2.16から2.1.14に変更しました。再度git push heroku masterを入力しても同じエラーが出ます。

またbundler -vと入力すると2.1.14なのですが、以下のコードでは、2.2.16で表示されているからなのでしょうか。（変更後のgit commit -mは入力済みです）

どうかご教授くださいますようお願いします。

remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Building on the Heroku-20 stack
remote: -----> Determining which buildpack to use for this app
remote:  !     Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
remote: 			Detected buildpacks: Ruby,Node.js
remote: 			See https://devcenter.heroku.com/articles/buildpacks#buildpack-detect-order
remote: -----> Ruby app detected
remote: -----> Installing bundler 2.2.16
remote: -----> Removing BUNDLED WITH version in the Gemfile.lock
remote: -----> Compiling Ruby/Rails
remote: -----> Using Ruby version: ruby-2.6.6
remote: -----> Installing dependencies using bundler 2.2.16
remote:        Running: BUNDLE_WITHOUT='development:test' BUNDLE_PATH=vendor/bundle BUNDLE_BIN=vendor/bundle/bin BUNDLE_DEPLOYMENT=1 bundle install -j4
remote:        Your Gemfile lists the gem pg (~> 1.1) more than once.
remote:        You should probably keep only one of them.
remote:        Remove any duplicate entries and specify the gem only once.
remote:        While it's not a problem now, it could cause errors if you change the version of one of them later.
remote:        Your bundle only supports platforms ["x86_64-darwin-20"] but your local platform
remote:        is x86_64-linux. Add the current platform to the lockfile with `bundle lock
remote:        --add-platform x86_64-linux` and try again.
remote:        Bundler Output: Your Gemfile lists the gem pg (~> 1.1) more than once.
remote:        You should probably keep only one of them.
remote:        Remove any duplicate entries and specify the gem only once.
remote:        While it's not a problem now, it could cause errors if you change the version of one of them later.
remote:        Your bundle only supports platforms ["x86_64-darwin-20"] but your local platform
remote:        is x86_64-linux. Add the current platform to the lockfile with `bundle lock
remote:        --add-platform x86_64-linux` and try again.
remote: 
remote:  !
remote:  !     Failed to install gems via Bundler.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote: 
remote:  !     Push failed
remote:  !
remote:  ! ## Warning - The same version of this code has already been built: a1fc89a646344ed22db737d016232699342837ee
remote:  !
remote:  ! We have detected that you have triggered a build from source code with version a1fc89a646344ed22db737d016232699342837ee
remote:  ! at least twice. One common cause of this behavior is attempting to deploy code from a different branch.
remote:  !
remote:  ! If you are developing on a branch and deploying via git you must run
remote:  !
remote:  !     git push heroku <branchname>:main
remote:  !
remote:  ! This article goes into details on the behavior:
remote:  !   https://devcenter.heroku.com/articles/duplicate-build-version
remote: 
remote: Verifying deploy...
remote: 
remote: !	Push rejected to cafery.
remote: 
To https://git.heroku.com/cafery.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/cafery.git'