S-100/S-701 torpedoes are being launched by pairs from the same tube on single fire mode

Recently, S-100/S-701 torpedoes tube is being fired twice in a row even if I selected single torpedoe launch.
There’s also almost no reload time because the spare torpedo is the one getting launched with the actual one meant to be launch alone.

To be more precise, it happens on the front launching tubes of these boats.