I can understand how you could see the problem this way, however you are wrong, nor does the wave front of the gamma burst expand at twice the speed of light - I believe this is where your misunderstanding.
Imagine a narrow gamma ray is emitted from a point source in a given direction, this wave travels at the speed of light (3x108 m/s). If a second ray is emitted exactly 180o in the opposite direction at the same time, the total distance travelled by the two seperate rays will be twice as far as an object travelling at the speed of light would travel in the same time.
However this is distinct from an object travelling at the speed of light - an EM wave is synomynous with a stream of photons, each of the rays will have an individual photon at their extreme ends - these two objects have individually travelled at the speed of light to their current positions. If we now consider the two waves as a whole we could not say it had travelled nor expanded at twice the speed of light.
Short answer:
A gamma ray burst is not in and of itself an object - it's a term we've derived for a sudden "explosion" of photons from a centre point, each travelling at the speed of light, and the burst as a whole expanding at the speed of light in any given direction.
Long Gamma ray bursts
No, gamma ray bursts do not occur on Earth. They are extremely energetic explosions from distant sources in space, such as collapsing stars or merging neutron stars. If a gamma ray burst were to occur close to Earth, it could have devastating effects on our planet.
Gamma ray bursts (GRBs) are relatively rare cosmic events. On average, about one GRB is detected each day in the observable universe. However, these events are unpredictable and can vary in frequency.
Gerald J. Fishman has written: 'Observations of gamma-ray bursts' -- subject(s): Galactic radiation, Gamma rays, Galactic cosmic rays, Bursts, Time lag, Isotrophy
If we consider the bursts of high energy electromagnetic radiation from stellar or galactic sources, we encounter bursts of X-rays and gamma rays. The two are similar in that both are examples of high energy electromagnetic energy, and both can be generated by certain stars or galaxies. Additionally, both are the result of nuclear reactions in the star or at sites within the galaxy. But with gamma rays, the sources may be fewer than with X-rays, and the gamma rays are higher in energy than the X-rays.
neutron stars and black holes
If we consider the bursts of high energy electromagnetic radiation from stellar or galactic sources, we encounter bursts of X-rays and gamma rays. The two are similar in that both are examples of high energy electromagnetic energy, and both can be generated by certain stars or galaxies. Additionally, both are the result of nuclear reactions in the star or at sites within the galaxy. But with gamma rays, the sources may be fewer than with X-rays, and the gamma rays are higher in energy than the X-rays.
The discovery of Compton scattering is the phenomenon where incoming gamma rays collide with electrons, resulting in a shift in the gamma ray's wavelength. This discovery helped confirm the wave-particle duality of light and demonstrated the particle nature of light.
Gamma ray bursts have the shortest wavelengths of any radiation in the electromagnetic spectrum. Therefore, x-rays have the longer wavelength.
Lisa Kewley studied cosmic rays and gamma-ray bursts.
Gamma ray bursts emitting light! What is meant by this? Any way gamma ray coming out of a radioactive nucleus is also an electromagnetic radiation as light but with very much higher frequency. Gamma ray also travels with the same speed as light does. According to Einstein's theory of relativity, no radiation can travel with a velocity higher than that of light
Gamma rays have the shortest wavelengths. Particularly those that form Gamma Ray Bursts, though to originate from outside our galaxy. Gamma Rays themselves have a frequency above 1019 Hertz.