All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
If you offered two prayers in combination after the prescribed time of the first prayer elapsed (Jam' Ta'kheer), then you would have to have had a legitimate excuse for doing so, and that excuse must have continued to exist until the time for the second prayer began. The second condition is to have the intention to offer the two prayers in combination during the first prayer’s due time before it is too late to offer it within its prescribed time. If you had the intention to combine the two prayers during the due time of the first prayer, then you would not have been obliged to have the intention of combining the prayers when performing the two prayers (in the due time of the second prayer).
You should thus know that your prayer is valid. You are not required to perform Sujood As-Sahw (prostration of forgetfulness).
Allaah Knows best.