2 NVIDIA A2 GPUs

I am buying Dell R740 Server and there is option to include two NVIDIA Ampere A2 (16GB) vs one NVIDIA Ampere A10 (24GB).
Which one is better ? I assume two NVIDIA Ampere A2 (16GB) will give me 32GB. How can we measure that ?
How these 2 GPUs will be linked without NVLink? which I assume it isn`t supported.