Many people mistakenly think that title tags and H1s can't be the same because of SEO. However, this isn't really the case. Some platforms such as WordPress.com don't even allow users to customize title tags, simply duplicating the H1 in its place.
Technically, title tags and H1s can be the same without having any negative effect, but it's still a good idea to make them different.
For instance, your H1 might be longer than the ~60-character limit that title tags have, making it likely to be cut off if used as a title tag. In these instances you'll probably want to shorten the length of your title tag, which may involve rewording it.
You can also attempt to rank for multiple keywords if you use different ones in your titles and headers, putting one long-tail phrase into the header and another in the title tag. However, if you do this, you should incorporate both keywords in the content to help you rank; a title tag keyword alone will do very little to help you if it's common.
Another argument for making titles and headers different is that you can include your brand name in the title, unlike most of your headers. If the title tag is short enough, it's a good idea to include your brand name at the end, e.g. "[What Content Is About] | [Company Name]".
Ultimately, having the same title and header won't have any impact on SEO efforts, but there are reasons you should make them different.