If two or more things are pledged, the pledgee may choose which he will cause to be sold, unless there is a stipulation to the contrary. He may demand the sale of only as many of the things as are necessary for the payment of the debt. (n) ARTICLE 2120. If a third party secures an obligation by pledging his own movable property under the provisions of article 2085 he shall have the same rights as a guarantor under articles 2066 to 2070, and articles 2077 to 2081. He is not prejudiced by any waiver of defense by the principal obligor. (n)