While its not usually advisable to share a crystal between ICs, it can be done if the following constraints are considered:
- The traces from the crystal to the ICs should be as short as possible.
- Proper care should be taken to ensure the impedance matching between the paths.
- Both ICs are configured to expect the clock as an input and not drive the crystal.
- Care should be taken to not overload the crystal with load capacitance.