Oh my god, such a big issue for a meager HRA receipt. I, being in accounts, have seen so many cases where the employee submits fake rent receipts for HRA exemption, and even the employer accepts it. Sometimes, the employer even encourages employees to give fake rent receipts.
HRA Exemption and TDS Deduction
Based on the declaration of the employee, the disbursing officer has to deduct TDS accordingly. Also, if the monthly HRA is less than 3000, then the DDO has the option of not collecting rent receipts and just giving HRA exemption based on the declaration. A rent receipt is not mandatory if the HRA earned per month is less than 3000.
Reporting to IT Authorities
Even if you report this to IT authorities, the company/employer will face more stringent action as, in spite of knowing they are a couple, he accepted their claims for HRA exemption. This might be in terms of tax planning; the husband and wife forgot to tell each other. According to them, they did not know the other is also going to claim HRA exemption. The maximum that the couple will need to pay is some fine with interest, that's all.