The pair were cited after the match and face a SANZAAR judiciary hearing. Super Rugby is taking a three-week break following this weekend's matches for the June test window.
Lavanini was sent off in the 25th minute for a dangerous charge when his shoulder hit Schalk Oelofse's head during a ruck and a try to Jaguares winger Emiliano Boffelli was reversed because of the incident.
Herrera was then sent off for a similar dangerous charge when he made contact with lock Steve Sykes' head while the Kings captain was on the ground in a ruck after 32 minutes in the match at Nelson Mandela Bay Stadium.
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The Jaguares eventually finished the game with 12 men when loose forward Tomas Lezana received a yellow card with 10 minutes remaining.
Referee Nick Briant awarded the Kings a penalty try immediately after Lezana was sinbinned before Dewald Human and Wandie Mjekevu also scored tries in the final 10 minutes to give the home side the victory.
The Jaguares hammered the Kings 73-27 in Buenos Aires less than a month ago.
Lavanini could face a lengthy ban for his latest transgression.
He received a one-match suspension in the first week of the Super Rugby season when he dropped his knee onto the Cheetahs' William Small-Smith when the centre was scoring a try.
(Reporting by Greg Stutchbury in Wellington; Editing by Peter Rutherford)
