This is from the IRS website so do your own research because this directly contradicts the answer given which is now also readible straight from Google but seems to be wrong based on this from IRS.gov
"Because a SEP-IRA is a traditional IRA, you may be able to make regular, annual IRA contributions to this IRA, rather than opening a separate IRA account. However, any dollars you contribute to the SEP-IRA will reduce the amount you can contribute to other IRAs, including Roth IRAs, for the year."
