Both Labourdonnais and Deschappelles were famous and very strong chess players. Labourdonnais beat MacDonnell in the longest series of recorded games played before Karpov met Kasparov, and the games are still famous and still anthologized. When you extend the world championship backwards, you find that Labourdonnais is the champion after Philidor and before Staunton.
Deschappelles was stronger than Labourdonnais, but he probably never played outside of France; Deschappelles was very very strong, and he also played Whist (the card game), in which he invented a play still in use in modern bridge; the Deschappelles Coup is rarely seen, and only strong bridge players (and some chess players, of course) ever have heard of it.
White may place these eight additional pawns arbitrarily on the third and fourth row. Only the white pawns that are on the second rank may make an initial double step.
RNBQKBNR RNBQKBNR RNBQKBNR RNBQKBNR PPPPPPPP PPPPPPPP PPPPPPPP PPPPPPPP ........ ........ ........ ........ ........ pppppppp .pp..pp. ..pppp.. pppppppp ........ .pp..pp. .pp..pp. pppppppp pppppppp pppppppp pppppppp rnb.kbnr rnb.kbnr rnb.kbnr rnb.kbnr
After experimentation, it was pretty well established by Labourdonnais and Deschappelles that 8 Pawns are much too strong; probably they played with five or six or seven extra Pawns. Five sounds like too few, but in fact the side with the Pawns has a positional advantage in addition to the material (a stronger Pawn formation!)