He really does actually. Double Team, as defined in most modern games , is "moving so quick you make copies of yourself." Best timeframe I can think of for this is 0.1 seconds, being the timeframe in which blur is perceived. As for distance, I'll assume Snorlax moves his body width, back to his normal position, and then another body length and back again. This is because the description of Double Team mentions there being multiple copies instead of just 1, and also lowballs the feat while staying within set boundaries.
Snorlax Weight - 460 kg
Snorlax Height - 2.1 m or 442 px
Snorlax Width - 507 px
507/442 = 1.15x
1.15*2.1 = 2.42 m
2.42*4 = 9.68 m
9.68 m/0.1 seconds = 96.8 m/s
KE = (0.5)(m)(v^2) = (0.5)(460)(96.8^2) = 2155155.2 J
Results
Snorlax's Speed - 96.8 m/s, Subsonic
Snorlax's KE - 2.155 Megajoules, Wall level