Force Field states "If the upgraded character would take 5 or more attack damage - Instead scrap this card and the upgraded character takes 4 attack damage." If we follow the exact text of this and we have 2 Force Fields on the same character. If the upgraded character would take 5 or more attack damage both Force Fields would trigger, then they would take 8 attack damage (4 from each Force Field) This doesn't seem like the intended effect of Force Field but following the exact wording, isn't this what should happen?
No. Force Field is a replacement effect, and only one of those applies at a given time. Once that happens, it reduces the initial attack damage to 4, which invalidates the second Force Field.

Source: Wizards of the Coast (2019-04-12)    【Link to Ruling】

Tags: Force Field, Force Field