Hi Experts,
 
In our salesforce application, we are using below objects.



Below are case records.



Perfect – If project having single case record, Total_Recurred_Hours__c showing correct value like 110 (i.e. 40+20+50).
Wrong – If project having two or more than two records, Total_Recurred_Hours__c showing wrong value like 160 (i.e. previous case record 110 value + 20 + 30). But it should be showing 20+30= 50 for second case record.

Below are my case record images

Case Record_1 for Rest Projet:



Case Record_2 for Rest Projet:



Anyone sort out my issue, Thanks in advance.
 
Thanks,
Manu