I'm developing a system that will be save on two different database

Hi Guys i just want to ask an alternative solution for my saving problem i'm saving data in two different database mssql and mysql . Mysql is my backups so every time the user will create an entry it they will be save in two database the user encounter a problem. the user added new entry then when they check the data it doesn't save so every time the user will create the same data it will result to duplicate entry because the data was saved firt in mssql then after that it will be saved on mysql any solutions may help thank you so much