I'm not necessarily sure how often people run into this conundrum:
I have two different professional careers. Should I have two LinkedIn profiles?
Some examples of people I've seen ask this question:
I took a few moments to let this question sink in, and marinate, just to try and figure out how I would use two LinkedIn profiles.
I couldn't find a reason. And it looks like other people have come to the same conclusion.
Imagine having two profiles, each one connecting to different people. How would you know who to connect with or what account to login to? Or, imagine having to duplicate invitations, doubling your work. Networking is hard enough.
I view a Linkedin profile as a place to share information about yourself even when you are not pursuing another full-time position. In that case, I would put both positions assuming there is no conflict of interest or other concerns.
LinkedIn is an extremely mature social network, and you should treat it as one. Don't beat around the bush, pretending that by day you're a mild-mannered reporter, and by night you're flying around the world saving Lois Lane (okay, well that's just in my dreams!). My point being, you don't have a secret identity, and if you did, would you really be putting it on social media? No.
My advice to you dual-career superstars? Put both careers in your LinkedIn profile. Why would this be bad? It's not unless you use the second job as a distraction from your other job. If you're a go-getter at both, your employers will see that as a benefit to having you on staff, not a detriment. It also tells your connections on LinkedIn what you're involved with. Someone may connect with you because you're on the board of the local "Green Thumb Social of America," rather than your professional experience "increasing efficiencies 54% in FY12, saving 13.5% on the allotted budget."
But don't take my word for it, what do you think? Take a look around your LinkedIn connections and I think you'd be surprised just how many are two, or even three-career superstars.