Triumph/Lucas would have known the implications of adding condensers at the coils and would have been aware that the amount of capacity needed to suppress sparking at the points and to minimise metal transfer either from the fixed contact to the moving one (or vice versa), is not some random value, having to be enough, but not too much.Fifty-plus years on, it's hard to know the real reason for four condensers (two on the points plate and two external), possibly simply to save scrapping a large number of 4CA points plates? Once the 4CA was superseded by the 6CA, there are only the two external condensers; as "Magnetoman" explains, not such good protection for the points but, given the external condensers' increased longevity, that the points were protected for longer was considered an acceptable compromise?
The later 6CA plate was a much better arrangement in a number of ways, also making the optimisation of the correct value capacitors simple.
However with the 4CA condenser terminal also being the anchoring point for the contact spring, existing 4CA plates were probably just left as they were. The condensers on the 4CA plates were physically quite small to fit in the space available, which possibly limited how much capacity could be crammed into the casing.
Perhaps the extra condensors at the coils were an in-production compromise to suit Triumph's in-service needs .
Regardless, these old condensers typically were made with rolled up layers of aluminium foil, interspersed with a paper dielectric soaked in a thin oil, like paraffin. Apart from the conditions these condensers were exposed to, all paper capacitors of that generation, are well known to dry out and deteriorate with age, even if lying on a shelf unused,
This makes any condenser 50+ years old on a bike suspect.