@Gomario
For messages you post, there's bridges like moa.party that let you post to Mastodon and automatically have it posted to Twitter.
But if you mean your feed (i.e. people you follow), I don't think either of the websites make that possible. I don't know if there's some third party app that combines and displays both feeds though, it's possible but I haven't heard about it 🤷♂️
#Twitter #Moa #MoaParty #birdsite #mastodonapp #mastodonapps