Anyone know this one? It's a question from another board.

Many moons ago - actually, in 1994 - I read a sci-fi novel that really gripped me... but I can't remember the title, and years of Googling/asking/bugging people on boards have not yet brought me any closer.

The book started with the crew of a deep-space exploration vessel waking up from hibernation. They had no recollection of who they were and how they ended up on the ship - all they knew was that one of the airlocks was open and alarms were sounding.

Using the main computer they found out they were half of the ships crew; the other half of the team was supposed to wake them weeks earlier (as part of a work/hibernate cycle), but had failed to do so, and the prolonged freezing had caused the minor amnesia. Apparently, their colleagues had abandoned ship in quite a hurry - though without obvious reasons.

The ship, meanwhile, had drifted into a system that looked remarkably similar to our own. Before landing, the crew theorized that they might have ended up in a starsystem that had accidentally developed into a "mirror" of the one we know. Upon arrival in Australia, they were horrified to meet themselves - as scientists of the Nazi space program; on the parallel Earth, WWII had a different outcome. After a narrow escape, the story gets foggier (well, it's been a decade), but there was at least a part with a "plant-planet" and a cliffhanger.

The story mentioned tape-driven computers and the tragedy of Apollo 1, so I guesstimate it was written between 1967-1975, give or take. Illustrated, though sparsely, hardcover and in Dutch, might have been translated. The title sounded foreign - for years I thought it was Terra Incognita but that doesn't give me any results. Any ideas ?