CONCAT function adding extra characters

[AI Rumman]

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.