How to check whether two different dangerous goods need to be segregated or whether they can be kept together in same container?
We are referring to packaged dangerous goods not bulk solids or liquids.
Example 1
Cargo no. 1 = UN 1263, PAINT, Class 3
Cargo no. 2 = UN 1158, ARSENIC, Class 6.1
Example 2
Cargo no. 1 = UN 1263, PAINT, Class 3 in limited quantities
Cargo no. 2 = UN 1158, ARSENIC, Class 6.1
Example 3
Cargo no. 1 = UN 1922, PYRROLIDINE, Class 3 Subsidiary Risk 8
Cargo no. 2 = UN 1806, PHOSPHORUS PENTACHLORIDE, Class 8
These are very basic checks of segregation, for practical purpose please refer to relevant entries in IMDG code for individual substances.
IMDG Code Compliance Centre 
Thanks Swapnil for notifying typographical error.. will correct it soon.
Regards/Shashi
please check the step 1 results of both the example 2 and example 3