Pendency of Another Action between the Same Parties (Litis Pendentia)

Under Rule 16 of the Rules of Court, pendency of another actions between the same parties and for the same cause is a ground for a motion to dismiss. What is the reason behind the rule?

Like res judicata as a doctrine, litis pendentia is a sanction of public policy against multiplicity of suits. The principle upon which a plea of another action pending is sustained is that the latter action is deemed unnecessary and vexatious. What are the requisites of litis pendentia?

[1] Identity of parties, or at least such as representing the same interest in both actions;
[2] Identity of rights asserted and prayed for, the relief being founded on the same facts; and
[3] The identity on the preceding particulars should be such that any judgment which may be rendered on the other action will, regardless of which party is successful, amount to res judicata in the action under consideration.
Lis pendens as a ground for the dismissal of a civil action refers to that situation wherein another action is pending between the same parties for the same cause of action. To constitute the defense of lis pendens, it must appear that not only are the parties in the two actions the same but there is substantial identity in the cause of action and relief sought. Further, it is required that the identity be such that any judgment which may be rendered in the other would, regardless of which party is successful, amount to res judicata on the case on hand. (G.R. No. 114928)