If my understanding of your current issue is correct, I guessed that the reason for your current issue might be due to the pass by reference. In this case, how about the following modification?
From:
array[i] = convert_date;
To:
array[i] = new Date(convert_date); // or new Date(convert_date.getTime());
By this modification, the date object of convert_date is copied.
If my understanding of your current issue is correct, I guessed that the reason for your current issue might be due to the pass by reference. In this case, how about the following modification?
From:
To:
convert_dateis copied.