At the time of his joining you should have collected from 11(which declares that an employee was or was not a member of the PF before joining your company) Now if the employee is asking for PF, you have two options.
1. Enroll the employee putting the actual date of joining, ie, 1-11-2019. You will have to contribute both shares of contribution, interest and damages. Since he had not asked for PF at the time of joining or had concealed the fact that he was a member of PF before he joined your company, then you should recover both employee's share as well as employer's share of contribution together with interest and damages as applicable for delayed deposit of contributions. As a proof of not disclosing the UAN at the time of joining, you should collect a form 11 dated 1-11-2019 in which he should declare that he was not a member of PF. Again with a present date you should collect another form 11 in which he should furnish his UAN and other details.
2. Enroll the employee now putting the date of joining as 1st May 2020. The period from Nov 2019 to April 2020 will be non contributory period. No need to pay past contributions and interests and damages. But you should collect 2 form 11, one dated 1-11-2019 wherein he would declare that he was not a member of PF and another one present dated in which he furnishes his UAN details.
Your defense when an Enforcement Officer asks should be like this:
The employee when joining did not disclose that he was a member of PF. The first form 11 is the Evidence in support of this. Since his salary at the time of joining was above Rs 15000, we did not cover him under EPF. Now he has come saying that he did not disclose his PF number at the time of joining due to oversight and requested that he may be covered. Therefore, we gave coverage effective from this month. We would have covered him right from November 2019 had he disclosed that he was an existing member of PF.
The second option, though legally weak, will be more beneficial for the employer. On the other hand, the employee would be interested to go with first option. Again, if he had declared that he was a member of PF right at the time o his joining and it was you who declined to give PF, then you will have to go for first option only and bear the costs. In such cases, you cannot even recover the employee's share of contribution.