If we use upper surface blowing and externally blown flap on the same wing will lift correspondingly be very high?
Two Engines Would Probably Be a Waste

First the basics about lift. Lift can be seen as occurring from one of two effects, a pressure difference across surfaces, or in reaction to the acceleration/deflection of the air (or whatever fluid you are moving through). Any case can be calculated from either method and you will come to the same result. You can't exploit a pressure differential without accelerating air, and you can't accelerate air without creating a pressure differential. Since force in these cases is governed by $F=\dot m\Delta v$ and required power is $P = \frac{1}{2} \dot m (v_{out}^2 - v_{in}^2)$. This means that to maximize efficiency you should try to accelerate the largest quantity of air by the smallest amount.

Now let's talk about flow control. Blown flow control systems increase lift in two ways, first is that they help keep the flow attached, and second, especially in propulsion driven systems like you are describing, is by deflecting part of the thrust downwards. Attaching the flow helps to allow greater angles of attack without stalling, once you have have generated this flow attachment, further actuation of flow control will not help generate any more lift by this method, though it may allow further angles of attack. If you are trying to improve low speed characteristics by allowing extreme angles of attack remember that the increase in lift will approximately follow a sin curve as it results from increasing the angle of deflection for flow across the wing, the first little increase in angle will give lots of lift with little drag, the last will give almost no lift for tons of drag if you want to take it as far as 90 degrees. Also lift is related to speed to a power of two, that means you need a lot more deflection as your speed drops.The second method that blown systems generate lift is by deflection, basically you gain some lift by sacrificing thrust. In the end this is no better than just pointing the engines slightly downwards.

If you want to perform flow control you also have to remember how much area on the wing your exhaust is going to effect. Your jet will likely be small in comparison to the total size of the wing.

At the end of the day, it is probably better to make a system that provides some flow control to the entire wing rather than a massive amount of flow control to a small portion of the wing so spread out those engines rather than trying to stack them; and remember, flow control will give no improvement over simple thrust vectoring at a standstill.