«أَمَدَّكُمْ ... أَمَدَّكُمْ ...»
He aided you ... He aided you ...
The repeated verb is purposeful. The first occurrence recalls blessings generally; the second turns attention to specific blessings. The repetition reinforces the act of benefaction while the absence of wāw between the clauses marks their semantic unity.
In the second clause «بِأَنْعَامٍ وَبَنِينَ» is governed by «أَمَدَّكُمْ». Its function is to specify the benefaction, not to introduce a different benefactor or an unrelated event.