Rule 707.9e

Some replacement effects that generate copy effects include an exception that’s an additional effect rather than a modification of the affected object’s characteristics. If another copy effect is applied to that object after applying the copy effect with that exception, the exception’s effect doesn’t happen. Example: Altered Ego reads, “You may have this creature enter as a copy of any creature on the battlefield, except it enters with X additional +1/+1 counters on it.” You choose for it to enter the battlefield as a copy of Clone, which reads “You may have this creature enter as a copy of any creature on the battlefield,” for which no creature was chosen as it entered the battlefield. If you then choose a creature to copy as you apply the replacement effect Altered Ego gains by copying Clone, Altered Ego’s replacement effect won’t cause it to enter the battlefield with any +1/+1 counters on it.