1128. When the characters of creditor and debtor are united in the same person, there arises a confusion which extinguishes the obligation. Nevertheless in certain cases when confusion ceases to exist, its effects cease also.
1129. The confusion which takes place by the concurrence of the characters of creditor and principal debtor in the same person, avails the sureties.
That which takes place by the concurrence of the characters of surety and creditor or of surety and principal debtor does not extinguish the principal obligation.