Yes, D415 uses Modified Brown-Conrady.
Others have modified (or 'extended') the Brown-Conrady model, suggesting that whilst the Modified Brown Conrady model may be unique to RealSense, modified models in themselves are not unusual.
A technical paper that had one of the 400 Series camera's engineers as an author says about the modified model: "The modification comes in the form of computing tangential terms with radially-corrected x, y. The open-source library for accessing the Intel RealSense cameras details the distortion model exactly".
Here is a link to the full paper:
Digging through the Librealsense code for Modified Brown-Conrady formulas, the closest I found to such a thing was the code below that is applied when Modified Brown-Conrady is the distortion mode.
const r2 = x * x + y * y;
const f = 1 + intrinsics.coeffs * r2 + intrinsics.coeffs * r2 * r2 +
intrinsics.coeffs * r2 * r2 * r2;
x *= f;
y *= f;
const dx = x + 2 * intrinsics.coeffs * x * y + intrinsics.coeffs * (r2 + 2 * x * x);
const dy = y + 2 * intrinsics.coeffs * x * y + intrinsics.coeffs * (r2 + 2 * y * y);
x = dx;
y = dy;