How to manage Resources in maintenance work order

Summary

i am allocating same resource to two work order at the same time. Logically it is wrong. Dont know how to manage it.

Content

i create 2 work order WO1040 and WO1041. Assign Resource instance "Fritz" for WO1040 for operation1  from 19May 5.00am to 6.00am. Assign the same resource instance "Fritz" for WO1041 for operation1 from 19May 5.30am to 6.30am

Both the Work order are executed and working fine.Cost accounting is also done without any error.

Logically when a resource is busy with one work order, how he can be assigned to another work order at the same time. But it is working.