Purchase and Sales Contract - Sale Pending Purchase Contingency

[David Morrow]

If BoB Noob (fictional person) has a signed Purchase and Sales Contract for property X with Dwayne, can BoB enter a 2nd Purchase and Sales Contract on that same property X with Larry.  The 2nd contract would include a clause stating that Bob's sale to Larry is pending BoB's purchase of property X from Dwayne?  One more detail...Bob has deposited 25k earnest money with Dwayne's title company. The property cost 100k.