No more than one vote?

Hi there,
I was trying your project on glitch and succesfully created a poll.
But as I try to vote from different browsers and IPs, I see that only one vote is taken in account.
Try it at https://livepoll.glitch.me/vote/6Uy0D8EymKk7ApAY

Did I miss something?

BTW, fsevent is a pain:
```
No Node version was specified; we are using default version 10. You can change this in package.json: https://glitch.happyfox.com/kb/article/59-can-i-change-the-version-of-node-js-my-project-uses/

Initializing node_modules, hold on...

/opt/watcher/app-types/node/install.sh: line 106: ((: <= 12: syntax error: operand expected (error token is "<= 12")

node v10.23.0, npm 6.14.8

Installing...

npm WARN deprecated fsevents@2.1.3: "Please update to latest v2.3 or v2.2"

> live-poll@1.0.0 postinstall /app

> husky install

On branch master

nothing to commit, working directory clean

npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@~2.3.1 (node_modules/nodemon/node_modules/chokidar/node_modules/fsevents):

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@2.3.1: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})

npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@~2.1.2 (node_modules/chokidar/node_modules/fsevents):

npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@2.1.3: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})

added 111 packages from 117 contributors, removed 49 packages, moved 325 packages and audited 467 packages in 72.124s

37 packages are looking for funding

run `npm fund` for details

found 0 vulnerabilities

Total install time: 87161ms
```

まず、別々のブラウザとIPを使って、リンク先の投票URLで報告された事象を再現し、その後、JavaScript/Node.jsアプリケーション内で投票を記録するエントリーポイントを追跡します。1票のみの動作が意図されたものか確認してください。完了とは、その動作が修正されるか明確に文書化され、回帰チェックでカバーされていることを意味します。

索引モデルが issue の本文から書いたものです。