Pastor Riley,

All my adult life, I've considered that it will happen exactly the way that you described:

1) That the two witnesses prophesy for 1260 days,

2) then the beast ascends and kills them,

3) and then the beast goes on for a subsequent 1260 days.

That their two opposing ministries are like bookends in time, defining a full seven year tribulation.

But, is there any possibility that each of their 1260 days is not back to back?

What if, instead of one of the beast's first acts, to kill the two witnesses, is actually one of his last acts?

I think the difference may hinge on the word continue:

Revelation 11:7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.

Revelation 13:4 And they worshipped the dragon which gave power unto the beast: and they worshipped the beast, saying, Who is like unto the beast? who is able to make war with him?

  5 And there was given unto him a mouth speaking great things and blasphemies; and power was given unto him to continue forty and two months.

If the word, "continue", in Revelation 13:5, only applies to continuing "after" the killing of the two witnesses,

then you would be completely correct in saying that the total, then, adds up to seven years.

However, if the word, "continue", in Revelation 13:5 is in relation to line 4, 

where it asks, " who is able to make war with him?", apparently some will fight against,

but utterly fail to stop the beast, then in that context, the word, "continue",

would show how the beast perseveres, regardless of who fights against him.

If so, then their 1260 days are possibly, concurrent, in parallel, rather than in subsequent, in series.

If that is possible, then while the beast operates, there is still a voice against him on the earth, actually two voices.

That would be very encouraging to those who decide not to take the mark, and may actually be what convinces them not to.

Also, the book is not always sequential, i.e. the beast doesn't rise twice, once in chapter 11 and again in chapter 13.

That is similar to the LORD not creating man twice in Genesis, once in chapter 1 and again in chapter 2,

but rather that chapter 2 goes into more detail of what was first mentioned in chapter 1.

Chapter 11 is physically located before chapter 13, in the book,

but couldn't they both be describing things happening at roughly the same time?

e..g. does everything in chapter 17 only happen after all those people are gathered at Armageddon, Revelation 16:14-16?

Or do some things mentioned happen earlier on? for example:

Revelation 17:10 And there are seven kings: five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space.

It doesn't mean that the seventh king still has not come yet, even when the troops are already at Armageddon, does it?