Have done sputum text already and the result came out negative... can this second x-ray requested from IRCC cause refusal of my application?
No
If the second x-ray is same as old one then it means it's not a Tuberculosis but some other patch or old tuberculosis which got cured on its own maybe in childhood,. The patch becomes permanent in some cases, yes it happens. So they will clear your medicals.
If the patch is not there in current xray, that means you had recent tuberculosis, which again calls for clearing medicals but they can ask for sprutum test after 6 weeks and xray all over again, sounds scary right?
So don't worry, 99.99% your patch will still be there and you will clear your medicals.
Do post here whatever is the result, cheers