The forgeries of these two stamp are not easy to spot especially the 1c stamp. Sometimes one has a good suspicion when the shade of colour seems wrong but as can be seen from examples here, the forgeries comes in different shades, some quite close to the original stamp.
The 1c stamp was issued in 1892. There are two constant dot flaws with the authentic stamp but they are so small that it is hardly worth discussing in practice. But the the forgery has two easy to notice features that make things a lot simpler. In case you are not sure, only the middle stamp in the upper lot and the first 2 stamps of the second lot of 3 are real. Again the fake thinner bar cancellation looks like the real thing.
The right side lion is the fake. There is a bare patch just above the first hind leg which is absent on the lion on the left. The forgery also has a "black eye" on the right ie left eye which can not be regarded as a constant feature and can also be present in a minor degree in the real stamp.
The bottom left ornament in the fake stamp is noticeably more centered to the left side as compared to the authentic stamp even though in the real stamp it is not exactly symmetrical and less obvious.
The 2c stamp was issued in 1889 and is catalogued in 2 shades. The one on the left is brown and the other one is lake brown. There are 2 constant flaws to take note and both are coloured dots.
There is a coloured dot to the upper left of 2 and another which is left of NORTH and above H in BRITISH.
The forgeries tend to be a lighter shade. The 2 in 2 CENTS is too close to the frame line above and also the bottom left ornament is centred towards the left side.
I was fooled by this one some years ago. It is not the £400 imperf between horizontal but a fake. The thick bar cancel is the giveaway here. These thick bar were said to be forged by Carame (Selsor, Sarawak Specialist Society).
Update 4 11 2018
I saw this sheet of 50 of 1c Fournier/Carame. It is hard to distinguish between these two. Anyway, there are lots of interesting errors here which I can show.
The stamp at the beginning of row 2, stamp 11 has the E which looks like that from the Greek alphabet.
This is the 6th stamp on row 3 or stamp 36 which has a C instead of ONE in the value tablet.