1. Create a new document, and a text frame with a misspelled word in it. For example, HavanaX, and then use Text > Spelling > Show Spelling Options. You'll see something like this:
2. Click on Havana in the suggestions, then on Change. You'll get this, as expected:
3. Now, click Change again. You'll get the following unexpected result:
Each time you click on Change you'll get another Havana added to the text. This seems to happen only with the last misspelled word in the text.