Event.clickCount

説明

同じ位置で何回マウスクリックをされているかを返す

Used in EventType.MouseDown event; use this to differentiate between a single and double clicks.

using UnityEngine;

public class Example : MonoBehaviour
{
    void OnGUI()
    {
        Event e = Event.current;
        if (e.isMouse)
        {
            Debug.Log("Mouse clicks: " + e.clickCount);
        }
    }
}