You can add multiple meta tags (or any other header code) by adding a custom header. To do that:

- Click on the menu: 'Page' > 'Page Editor' and choose the 'Header' tab.

- Click on the 'New Header' button.

- In the 'Custom Header' area, add your meta tags (or other code) in the regular form:

e.g.
<meta name="Test1" content="TestData1">
<meta name="Test2" content="TestData2">

- Press OK.

That's it