What are the odds of both transactions being included in the same block?
Zero. Such a block would be invalid, since it spends the same coins twice.
If both transactions are valid then both transactions can be included in the same block too if the fee is used in the same range then what happens?
The default behavior of a node is never have two or more conflicting transactions in its mempool. When it accepts a replacement, it evicts the original. As such, it would never create a candidate block which contains two conflicting transactions. Should some mining pool edit their software and accidentally mine a block containing conflicting transactions, all other nodes on the network would reject it as being invalid.