To my mind the difficulty here is the use of the word "penal" in relation to wrath. Ephesians 2:3 ("Among whom also we [the elect] all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.") paired with John 3:36 ("He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him.") should clear the difficulty. By nature every person is a sinner and in rebellion against God and God's wrath is towards all sin (and sinners as sinners). However, Christ paid the penalty for the sin of His elect and therefore the wrath of God will not abide on them: they will be converted in due time and justified and vindicated on the Day of Judgment. Whereas those who do not repent will ultimately receive the just, eternal punishment for their sins: the wrath of God will abide on them. Whilst it's true that all sinners (the elect and the reprobate alike) suffer the consequences of their sins in this life to some degree (some more than others, and the elect will be kept from the soul-destroying consequences of sin) the truly penal aspect of the wrath of God is not applied until an unrepentant sinner dies. So the elect are not under penal wrath before they are converted (they are not paying the full price their sins deserve, which is an eternity in Hell) therefore they are not paying for their sins again. Even converted sinners are subject to the Lord's chastisement. But what Christ paid on the Cross was the eternal penalty that the sins of the elect deserve and therefore the punishment of eternal damnation was removed from off them, the Law being satisfied by Christ's sacrifice.
The introduction of the word "penal" merely confuses matters. Scripture doesn't ever use the term "penal wrath" as far as I know so we should avoid it as well. Of course the concept is there (hence penal substitutionary atonement) but when we start using the term and applying it to the Lord's people (which Scripture tells us were the children of wrath as others are) then the use of the phrase causes trouble.