CONCAT function adding extra characters

[AI Rumman <rummandba@xxxxxxxxx>]

I am using Postgresql 10 and seeing a strange behavior in CONCAT function when I am concatenating double precision and int with a separator.

select concat('41.1'::double precision,':', 20);
Result:
41.1000000000000014:20

Value 41.1 which double precision converts to 41.1000000014.

Is that expected?

Thanks.