Usually yes. The best way to test it is to take a ruler and wrap the two strands together around the ruler continuously for one inch length (make sure the yard does not overlap, nor leave gaps). Then take a strand of chunky yarn and do the same. You should get the same number of rotations around the ruler for each.
You may also want to note that using two yarns together of different colors will give you a nice heathered effect in the finished product.
If you are making an item where it is important that it come out exactly the same size the pattern indicates, then you need to make a gauge swatch to be sure you are choosing compatibly sized yarns. Not all medium weight yarns are equal, nor are all chunky weight yarns equal.
You can find yarn weight information at the Craft Yarn Council's web site.
In general terms
Two strands fingering equal one strand sport.
Two strands sport equal one strand worsted.
Two strands worsted equal one strand bulky
Chunky and bulky are similar but not equal. Chunky is considered #5 and Bulky #6.
Unfortunately, both dk and chunky yarns vary in thickness quite a lot. In general, two strands of dk would be slightly thicker than most chunkies. If your pattern is not too size sensitive, you'd probably get away with it. There is a yarn comparison chart on Ravelry which gives some useful information, but the only way to be sure is to make a size swatch.
Because the number of A doesn't not T and G does not equal C. It isn't double strands so it does not have to equal each other.
do you mean dk or double knit yarn ? if so this is basically equal to USA sport yarn. It is non American version and knits at between 5-6 stitches to the inch using a number 5 - 6 needle ........ OR ..... did you mean just using the yarn double as in using two strands at once? if your pattern says use the yarn double then just use two strands at once by pulling from two skeins and holding both threads together when your work .
do you mean dk or double knit yarn ? if so this is basically equal to USA sport yarn. It is non American version and knits at between 5-6 stitches to the inch using a number 5 - 6 needle ........ OR ..... did you mean just using the yarn double as in using two strands at once? if your pattern says use the yarn double then just use two strands at once by pulling from two skeins and holding both threads together when your work .
Double 15 is equal to 30
Yarns are very variable, but in the US this is often called worsted weight. Personally I find DK tends to go further than a worsted weight yarn. I always check with a yarn swatch when using DK for a US pattern, as I often have to use a different hook size.
A2 has double the area of A3, with a width equal to the length of A3 and a length equal to double the width of A3
OSB stands for oriented strand board. It is made of wood strands and waterproof adhesives. The strength of OSB board is equal to that of plywood.
Since a quartet equal four, a double quartet would equal eight (4+4=8).
two times a negative number does not equal 0.
Double price is equal to 200% of the original price.
Usually it is the cook checking to see if the pasta is "al dente" or a kid stealing a taste as they pass through the kitchen before supper. one piece of spaghetti? what else!
a double hernia