[PD] why do i get artifacts in gem?

[punchik punchik]

Hello, in my gem patches when i have 2 or more  geos that overlap i always get artifacts or glitches between them, why does these artifacts appear? is there any way  of avoiding them?

ive tried the same patch in 2 different computers and i get the same results, any idea?
 please check pics:

http://www.hypermilk.net/artifacts/Imagen%201.png
http://www.hypermilk.net/artifacts/Imagen%202.png

thanks


pun.