I was having this issue in MC18. In MC19 it gives me the window in the lower right notification window and when I click on "Close" the Securerip info window pops up and that allows me to close it which allows me to rip the next CD.
I don't remember if it would have been possible to get to that in MC18. Check on the lower right and see if there is a "CD Ripping" window available there.
The other thing that helped me was turning off the auto eject which seemed to help. Also if you minimize and maximize a couple of times sometimes you can get that securerip dialogue up and close it. If all else fails Closing MC18 (From the taskbar) will produce the dialogue which you can close and then re-opening MC18 and continue ripping.
Something I did not try when I had MC18. In MC19 in "Options", "CD, DVD & BD" under each drive there is a "Copy Mode: Secure" I am pretty sure if you turn this off it will resolve this issue for you as a work-around.
Carl.