Something like:
B3: F01 F03 F06 F67
A8: F03
A9: F08
Validation rule: =NOT(ISERROR(FIND($A8;$B$3))) applied to B8 and B9
Result - input allowed in B8 and not allowed in B9
Something like:
B3: F01 F03 F06 F67
A8: F03
A9: F08
Validation rule: =NOT(ISERROR(FIND($A8;$B$3))) applied to B8 and B9
Result - input allowed in B8 and not allowed in B9