CORONA SDK LUA HELP..... COLLISION ERROR

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Lua

Hi,

in my game i have created a collision function, in this game multiple eggs fall from the sky and when they collide with the "ground" i want them to disappear .. the problem is that when the first contacts the ground it disappears but the rest of them don't.. can you pls help me?
COLLISON CODE:

  function onGroundCollision( self, event )
   if ( event.phase == "began" ) then
        if(self.myName == "egg") then 
            if(event.other.myName == "ground") then
                audio.play(sound3)
                
                    self.isVisible = false
                    self:removeSelf()
                end                    
            end
        end
end

FRAMES CODE:
this is the code that drops multiple eggs:

local function onFrame(event)    
frameCounter = frameCounter + 1
if(frameCounter % 40 == 0 and eggCount > 0) then 
        eggCount = eggCount - 1
        local egg = display.newImage("egg.png")
        egg.x = math.random(0, 310)
        egg.y = 0
        egg.rotation = math.random(0, 360)
        physics.addBody(egg, {density = 2.0, friction = 1.5, bounce=0.01})