This bug is consistently reproducable throughout the hour.
During an hour in which the Kills This Hour said I produced 1673 kills, I was able reproduce a double kill on Ancient Zombies, Demon Scorpions, and Brown Crystal Guardians approximately 15% of the time I had spawned and subsequently chosen to quick fight the monster. On one occasion, I was able to produce a triple kill.
I was fighting using my character El Sinister (#3288) in the N'rolav Endless Desert areas #2665, 2666, 2667, 2668, 2669, 2670, 2671, 2672, 2673. These areas produce the north/south column on the far east end of the desert here.
I can confirm from further testing after that hour, when I produce a double kill, I am netted double the gold for that monster.
When double killing a monster with drops, two items were dropped. These occured fighting the Brown Crystal Guardians, and usually dropped 2 Dull Acient Crystals. However, one instance on a Brown Crystal Guardian netted a Dull Ancient Crystal and a Red Ancient Crystal.
Further testing with another character, Cerberus (36409), on Ravenous Sharks (in Areas 1672 & 1673, the far east end of Midnight Beach) also showed that with a double kill two items would be produced and not necessarily of the same type.
I did not have any instances of Treasure Boxes dropping during that hour or further testing. So, I am unsure how they are affected. I would imagine that you are twice as likely to have a Box dropped, since you are inacting two kills. As opposed to getting 2 Treasure Boxes to drop. This is inferred from the previous report that monsters that drop items consistently will reward 2 items of different types.
Often, while attempting to reproduce the bug, the server would not return a double kill. Instead the order of the combat report text would be altered, such that rounds of combat would at times be reported after the defeat and gold/xp collection from the combat.
In the past, but not tested today, I had found on occasion that when doing regular "Attack" combat for the purpose of experience gains it was also possible to produce a double kill. In those instances, I believe double gold would be retrieved, but the experience return would be slightly different. The combat report would indicate full experience return for the first of the kills and then experience return of a much smaller amount (that which would be awarded if the character had retreated and come back and dealt one attack resulting in a kill and reduced experience). Because experience is only shown to the player in terms of percentages, I am unable to test and report if double kills return experience reward the character the additional experience from the second kill.
El Sinister has about 100 Plat netted from the bugged double kills that can be removed from his purse. I can do this myself if an Admin wishes not to waste his/her time.
The Red Ancient Crystal was the lower of the item #'s between it and the Dull ancient crystal during the double kill, therefore I believe it came from the real monster. I subsequently have already turned it into the Golden Age Knowledge Machine and turned it into gibberish. Any additional items produced from the bug have been left to rot.
I am uncertain if the practice of double killing is faster for farming of platinum. Getting almost 1700 kills is generally no small feat, but it is not my highest and still 300+ short of the highest kills per hour that I know of (obtained by Kalea). When the double kills occur, it forces the server to spend more time processing scripts and the result is a slower return of files to the querying browser (that is what I have observed). While getting two kills on one spawn would seem beneficial to obtaining plat, the subsequent slowdown may or may not result in less kills per hour. However, it certainly can be assumed that when fighting infrequent spawns and even one time drop bosses, a double kill resulting in double items is definitely a beneficial abuse.
Further, during that hour of heavy killing, I had noticed that the server responded slower during each change of the Marc and I was more readily able to produce the bug. This is in addition to the normal server stall at the hour changes. During the second half of the Marcs, the server also seemed to respond faster on average and the bug less likely to occur.
I was running IE6 on a cable connection while performing the test. On http://darkgrimoire.com
. Not www and not www2.