Safari IOS duplicating numbers on input text when using a Japanese Kana keyboard

I'm facing an issue where an input gets duplicated when using a Japanese keyboard.

It's fairly simple to reproduce.

• Add the Japanese Kana keyboard to an IOS device.
• Open an HTML page with a regular input text on it.
• Change the view of the Japanese Kana keyboard, so you can type regular numbers (1, 2, 3...)
• Type the same number twice. Eg: "22"
• Confirm the composition

Expected behaviour: The input value is "22"

Current behaviour: The input value is "222" being the last "2" another open composition.