The dots on the bottom are a prunt over the pontil mark which is quite an untypical finish for Leerdam. For my vase it is all a bit too late - it developed a spontaneous crack from rim via handle almost all the way to the bottom - so I'm wondering when it will disintegrate. It points at sloppy annealing, which is un-leerdammish. Likewise the colour, btw.
I'm also not sure that it is Copier - even if the example you found is allegedly etchmarked with the LC logo. Handled vases of a more convoluted nature were made by Joep Nicolas in 1940; the CL mark would place it earlier in time and in the category of production glass. I can only say hmmmmmmm........ or to quote my grandfather, I'll need to see it first.