H4-stamped but last case is still pending

In November 2018 my last H1B extension got approved but my dependents H4 applications are still pending meanwhile we went to India and got stamping for all (including dependents). If i file extension for my dependents will it impact the approval since the old case is still pending and the I-94 number is mismatch?

No, it should NOT impact. You can send a request letter to withdraw the old ones stating the reason. Check below.