Something like this?
# example data
r <- raster(ncol=10, nrow=10)
r[]=1:ncell(r)
x <- brick(r,r,r,r,r,r)
x <- x * 1:6
y <- list()
for (i in 1:nlayers(x)) {
r <- raster(x, i)
y <- c(y, r, r, r)
}
s <- stack(y)
solved copy rasters within stack