It is not possible to install more than one HubSpot tracking code on a single website. In the event that there are two installed at one, the first one to load will be the one that remains active and any subsequent tracking codes will not initialize.
To identify what you have installed on your website, it is best to use your browsers in-built development tools. In Chrome, for example, you can right click on any part of your website and click Inspect. This will bring up Chrome's Developer Tools on the Elements tab. Here you can search for [your Hub ID].js (e.g. 369684.js) which will show you all the tracking codes installed on the website right now.