Moses did not see God's face, the use of "face to face" was to put it into human terms. Joshua who also was there but he never left the tent but remained inside while Moses went out to talk with the LORD to be in His presence, but did not look into His face.
For God when he passed by Moses covered Moses' face so he would not die.
Ex 33:23 "Then I will take My hand away and you shall see My back, but My face shall not be seen."(NASB)
Hope this was helpful.
Peace be with you,
Your Brother in Christ,
"A new commandment I give to you, that you love one another, even as I have loved you, that you also love one another. By this all men will know that you are My disciples, if you have love for one another." John 13:34,35