Charts of twins (or of time twins) have always been a problem for astrology. Especially in our day and age that, due to the fact that caesarian sections have become very common, twins are very often born perhaps less than 4 minutes apart, the time required for a change of one zodiacal degree. It is one of the arguments people very often use to discredit astrology.
So what do we do wih these charts? Even fixed stars seem unable to solve the issue in many cases, if we allow a small orb. We don't get much help either from twins themselves, who insist (sometimes too much) that they are completely different. There have been some approaches suggested by various astrologers (for example, in a chart with a Moon/Saturn opposition one twin tends to play the part of the Moon and the other the part of Saturn), but the validity of these theories remains to be seen.
In the case of the Gibb brothers we have no such problems as they were born 35 minutes apart. (22 December 1949, Douglas, Isle of Man, 03:15 -Robin and 03:50 -Maurice). Maurice died on January 1st, 2003 and Robin died yesterday. Both brothers died of problems with the intestines. Virgo and the 6th house rule intestines in astrology and in their charts, the 6th house is in Aries and its ruler, Mars, is in Virgo. Mars in Virgo, in general, is also associated with the belly (and legs). The fact that this Mars is at the end of Virgo makes it even more dangerous (see Richard Saunders).
What's even more impressive, is that both brothers - although nine years apart - died at the exact astrological time, when secondary progressed Ascendant was at 12o Sagittarius and progressed MC was conjunct Neptune! We can make an argument out of the Neptune/MC conjunction (Neptune is against material reality), but still it's not very convincing as a stand-alone factor. Even in modern astrology, we would have preferred Pluto, for example, who, by the way is conjunct the natal MC of the two charts.
What about the progressed Ascendant degree? What's so special about it? It's still quite far from squaring Saturn and it sextiles natal Venus, Robin's 8th house ruler, but not Maurice's, whose 8th hosue ruler is Mercury. Even if that were the case, a simple sextile isn't much of a testimony.
The interesting thing about that degree is that it's the degree of the Nodes. The natal Nodes are on the Aries/Libra axis and there's a theory that says that the degree of the Nodes is generally critical/important in all of the signs. I haven't tested this theory and I cannot vouch for its validity. The twins' progressed Ascendant trines/sextiles the natal nodal axis.Wouldn't a conjunction be preferable? Probably.
Still, it's pretty impressive isn't it? The "coincidence" of it!