Justice League of America#47(1991)

As the Spectre uses all his power to keep both Earth-One and Earth-Two from crashing into each other as a result of the Anti-Matter Man's travels, the JLA and JSA members on Earth-One and Two recuperate after their battles against Blockbuster and Solomon Grundy. However, the space warp cause Solomon Grundy and Blockbuster to transport back to their original Earths. This time forcing Green Lantern, Flash, Hawkman, Black Canary and Dr. Mid-Nite to fight Blockbuster on Earth-One, and Batman, Dr. Fate, Sandman, and Wildcat to battle Solomon Grundy on Earth-Two.

Warned by his crystal that something is amiss, Dr. Fate transports the JLA and JSA members to the warp between two worlds and attack the Anti-Matter Man, but their efforts have no effect. Meanwhile finally left alone and able to become the Atom, Ray Palmer realizes that his lab assistants cosmic-scanning device was the catalyst that caused the Anti-Matter Man to attempt to travel into the positive matter universe.

Traveling to the cosmic rift, the Atom uses his scientific knowledge in conjunction with the Spectre's magic to break the warp, shunting the Anti-Matter Man back to his Antimatter universe and restore order to both Earth's. Returning to Earth, the group finds that while they were battling the Anti-Matter Man, Green Lantern transported Solomon Grundy and Blockbuster to the same Earth, where they have been battling each other since they were pulled away. They arrive just in time to see the two suddenly stop fighting and become friends, and decide to return to their own Earth's peacefully to be returned to custody.