Gordon Stanger's answer has already made perhaps the main point: There's absolutely no reason to believe that the evolution of a planet in one part of the Solar System should exactly mirror that of any other planet. We see drastic composition and size differences among the terrestrial planets; why should any other properties be similar?
I'm aware of several possible mechanisms that explain why Venus spins so slowly.
Repeated impacts and the formation (and death) of a moon
Venus has no moon - a curious fact, considering that the only other planet to not have one is Mercury. You could ascribe this to many factors, such as relatively low masses and close proximity to the Sun. However, some models have suggested that there was a moon around Venus, which is now gone.
Alemi & Stevenson (2006) proposed a complicated story of impacts. Their model suggests that Venus suffered a giant impact from a moderately sized protoplanet. As was the case with Earth, debris was thrown up, and a moon coalesced in orbit. This changed Venus' rotation, and began to transfer even more angular momentum to the moon. However, a second impact to Venus reversed its rotation, and the moon fell back to the planet, transferring its angular momentum back. This would all happen on the order of ten million years or so, starting and possibly ending during the Late Heavy Bombardment.
The upshot of all this is that Venus emerged with not just a retrograde rotation, but a much longer day. This is, of course, not the sole explanation for the retrograde rotation - exotic scenarios involving 180 degree flips have been proposed; see e.g. Correia & Laskar (2001) - but the impact hypothesis does have the added advantage of explaining the lack of a moon.
Atmospheric tides and internal friction
Interactions with the Sun have also been proposed as a mechanism affecting not just Venus, but exoplanets like it. Atmospheric tides, generated through heating and cooling from the Sun, could enact a torque on the planet, bringing it into one of several "equilibrium states" (see Auclair-Desrotour et al. (2016)). Internal friction could cause more complex interactions in the mantle, further exaggerating the effects on the solid part of the planet. The same thing could happen to any planet orbiting the Sun at roughly the same distance as Venus in the Solar System.
It was once proposed that an additional torque was applied to Venus by Earth, complementing the solar atmospheric tides, as there appears to be a coupling between the time between close approaches to Earth and the time of one Venusian day. However, it has since been determined that such a resonance does not, in fact, exist, and should be discounted as a possible reason for the slowing of Venus's rotation (see Shapiro et al. (1979)).
Why not Earth?
So, why would these effects happen to Venus but not Earth? The chaos of the early Solar System is of course the best answer, but there are other explanations for the specific proposals. The impact theory simply relies on randomness: While Venus and Earth were both likely to suffer major moon-forming collisions, they were not as likely to go through this twice. The atmospheric tidal effects, on the other hand, could have been unavoidable, as interactions with the Sun may have been more severe with Venus, for a variety of reasons including distance to the Sun and the exact properties of the atmosphere.