@ Dayanithi,

Based on the numbers gven by you

If horse was assigned 53 Kg with a Rating of 30 What it means ? As rating is 30 in 20-40 race with Bottom weight as 50KG then at Rating 30 it should be assigned 50 +(30-20)=50 plus 5 kg but it is runnung at 53 Kg which means for this race is Weights are Lowered by 2 Kg (55-53)Kg

In the second race at same Rating it caried 59.5Kg so Bottom Rating of the Race is 30-19=11 which means it is a Race with Weights Raised by 4.5Kg which is (20-11) assuming that this is also 20-40 race

The apparent differences in Weights has no effect as Weights of all horses will be adjusted accordingly.Only effect is the Times Clocked in both races are not comaparable unless adjustments are made for the Weights Lowering/Raising as the case may be 

Hope your query is answered.

Which Race ?

Which Centre?

If it is the top rated horse in that race it gets too weight compared to the lowly rated horse in the field with bottom weight. Weights are assigned relative to their rating in a field. 

Penalty for winning and placings are different matter.

Handicape races run on so many things.may certain increase of weight due to rest of horse filed or pervious ran company.i can bet even handicaper who designed card also failed to catch a real winner.all software engineers failed,only bill bentor succeed but he took inside information to add in further calculation,he never bet win and place only ,he played jackpots, forcast,tanela etc.horse racing is not for one horse and here all punters failed.