No, a shared library may only be accessed by one user at a time.

Can two users share a library and both play at the same time? For example, titles that require an additional third-party key, account, or subscription in order to play cannot be shared between accounts. No, due to technical limitations, some Steam games may be unavailable for sharing. Can all Steam games be shared with friends and family? Libraries are shared and borrowed in their entirety. Can I share specific games, or do I have to share my whole library? You must be online to access and play games which are shared with you. Do I need to be online to play a shared game? You may authorize Family Library Sharing on up to 10 devices at a given time, and for up to 5 accounts that may then use your game library on any of your authorized computers. Is there a limit to the number of devices or friends I can authorize to share my Library? Then enable the sharing feature via Settings > Family, (or in Big Picture mode, Settings > Family Library Sharing,) where you'll also authorize specific computers and users to share. To enable Family Library Sharing, first be sure you have Steam Guard security enabled via Steam > Settings > Account in the Steam Client. Frequently Asked Questions How do I enable Family Library Sharing on my computer?

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