It's allowed, but I wouldn't simply duplicate it because you can run afoul of Duplicate Content rules.

Here's a short article I wrote about this exact thing.

https://medium.com/swlh/how-to-repurpose-content-without-being-penalized-by-google-bots-9962098cd73f

Try to rewrite it a bit to suit the other site. For example, Linked In - you could give your piece a work perspective or make it relevant to an employee.