Firstly, yes, I know, it is an image alt attribute but as John Mueller of Google said on Twitter having your title tag read exactly the same as your image alt tag on the same page is not an issue - it might be duplicate but it is not an issue for Google search.
John said while "it's duplicate: it is "not an issue." Here are the set of tweets:
It's duplicate, but not an issue.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) May 23, 2018
In fact, I know a lot of CMS platforms and humans who copy the title tag from the page and place it in the featured image on the page as well.
This is really not an issue, but you should reserver the image alt attribute for describing what the image is about.
Forum discussion at Twitter.
