Is the testimony of a former agent accepted concerning the matter in which he previously held agency after his removal?

Primary text

If an agent testifies concerning a matter in which he formerly held agency after he has been dismissed, his testimony is not accepted, regardless of whether he engaged in litigation concerning that matter during his tenure or not. The evidence supporting this is that by the contract of agency, he became an opponent in that matter, thus precluding his testimony, similar to one who has actually litigated in the matter. This situation differs from a matter in which he was never appointed as an agent, as in that case, he was never considered an opponent.