Ms Viande said she became aware The Dice Jail, in Queen Street, was broken into after passers-by spotted the front door was smashed on the morning of 25 December.
“Somebody smashed through the glass on the front door using a hammer and stole a lot of [Pokémon trading card] stock,” she said.
“I am pretty upset, annoyed and angry. I am disappointed more than anything.”
Ms Viande said the break-in happened at about 04:40 GMT.
Thieves then broke into Ms Viande’s other store, in Forest Street, Sutton-in-Ashfield, at about 03:45 on 26 December.
“They went to one of our side windows and threw a big metal ball through the window, disintegrating it,” she said.
Ms Viande said the thieves then stole a cash drawer from the till and targeted trading cards again, including Pokémon, Star Wars, Spider-Man and Warhammer.
“We managed to actually see them in the act of doing it [on CCTV] and managed to call the police while they were in the shop,” she said.
Police said officers attended two minutes after the call came in, but the thieves had left the scene.
However, the majority of the cards were recovered by officers after the suspects fled the scene and dropped them.
Other cards have also been located stashed in a nearby street, police added.