If I have entered a T4A for $1900 for an AB scholarship under T-Slips Box 105, do I have enter this same amount or an exempted amount on Line 130 too?

When you enter $1900 on Line 105, on T4A, assuming you entered it in Elementary and Secondary Scholarships box (High School Rutherford Scholarship), you will get a tax exemption for full-time education on form "Other".