Link doesn’t work after first time

Great plugin!

But we realize that the link doesn’t work after the first click.

For example:

I click the link https://www.oursite.com/cart/?fill_cart=20825,21981,21151
and perfect, it adds correctly the 3 products.

But if I like to click again the link or I remove one product or I clear the cart and than I try to click again on the link …nothing happens! no product is added to the cart after the first use of the link.

Are you aware of this behaviour or it is our specific problem? thank you! ??