Some cards were originally mistranslated from their original Japanese versions. Furthermore, for old sets, tcgone is based on an old official compendium and also on erratas with some later changes.
Compendium link: WotC POKÉMON TRADING CARD GAME RULINGS COMPENDIUM
Erratas uses in TCGONE link: WotC Erratas, Complete List
If you filter “PINECO” in that compendium, you will find the following…
== BURST (Pineco - Neo: Discovery Expansion)
** Here’s how it works. There are actually 2 flips! The attack does 40 damage [to the opponent]. Then flip a coin, if heads the attack ALSO does 40 damage to Pineco AND 10 damage to each benched Pokemon. Then flip another coin, if that second coin is tails, then this attack does NOTHING (not even the regular 40 damage). So there are three possible results:*
First if both coins flips are tails, the attack does nothing.
If the first one is Heads, and the second is tails, this attack STILL does nothing!
If the first flip is tails and the second is heads, the attack does 40.
If the first is heads, and the second is heads, the attack does 40, and 40 to itself AND 10 to each benched Pokemon. (May 31, 2001 WotC Chat, mid-point Announcement)
Q. So for Pineco’s Burst attack, if I flip tails first what happens? Does the attack do nothing or do I flip for the 2nd “flip a coin”?"
A. Go to the second flip. If you got tails on the first flip, the attack will still do the regular 40 unless you get tails on the second flip. (May 31, 2001 WotC Chat, Q253)